The TPMS thread got me thinking about the causes for bus crashes. As a noob here there seems to be a lot of discussion about tires. Mostly failing tires mess up the fender and undercarriage but rarely do buses crash off the road, flip, or otherwise sustain major problems.
Obviously, it is vital to have tires that are safe. "Old" or "aged out" tires has no clear specification to define when they are no longer safe. The CHP has vehicle inspection stations along the highways, one goal is ensuring heavy trucks are safe to travel on the road. If the CHP deems a truck road safe, that is a green light for me. Interesting, that the CHP does not check tire dates, only condition. This is from a first hand conversation with an inspection officer at the Fairfield station.
https://www.fmcsa.dot.gov/safety/research-and-analysis/large-truck-crash-causation-study-analysis-brief (https://www.fmcsa.dot.gov/safety/research-and-analysis/large-truck-crash-causation-study-analysis-brief)
First off, 87% of heavy truck crashes are driver related. Of non-driver related causes, Table 2 lists 19 causes for heavy vehicle ( > 10k). Number 1 (29%) is brake related. Bad tires is near the bottom (6%).
Back to tires. Common causes of tire failure are underinflation, irregular wear due to mechanical issues, and road hazards.
https://www.tires-easy.com/blog/top-causes-of-tire-failure/ (https://www.tires-easy.com/blog/top-causes-of-tire-failure/)
http://www.truckinginfo.com/channel/maintenance/article/story/2013/06/5-deadly-tire-sins.aspx (http://www.truckinginfo.com/channel/maintenance/article/story/2013/06/5-deadly-tire-sins.aspx)
This is just as an FYI, not meant to start as long dialog about yeah but.. as there are plenty differences between commercial truck drivers and we recreational drivers. Just thought it was interesting for me as I search for coaches that have older "aged" tires that appear fit for duty and keeping that in perspective with all the other factors and criteria being weighed before choosing a coach.
For example, after this analysis, I'll put far more weight on a documented well done full brake job over some "old" tires. I feel a lot better that common sense and frequent visual checking of the tire's condition will suffice. Common sense tells me failing brakes is a far greater potential serious hazard.
I'm sure a lot are going well duh.... but again as a noob trying to find the right compromises it has been a useful diversion. I suspect a few others may readjust their focus too.
It is true that most bus nuts do not have the professional driving experience that myself and a few others have. It explains a lot of newbie questions and comments. It is a lot worse on Facebook than this board. And keep in mind that most people behind the wheel of an air brake class A motorhome don't have a lot of knowledge or experience driving it or maintaining it or understanding that air system, or brakes. Also a lot of those people only use the RV a couple of weeks a year.
It is true also that the age of tires, in commercial or private use, is ignored in the US and Canada. I have a CDL for tractor/trailer and buses, and in either case, it is not required to check tire age during the pre trip inspection. Only condition like tread wear, correct inflation, and damage. And, like you point out, DOT doesn't care either, anywhere that I am aware of.
Yes, most accidents, in commercial or private vehicles, are caused by driver error, negligence, inattention, distraction, etc. Most tire blow outs are caused by under inflation that creates heat. That could be largely prevented by paying attention to the tires. TPMS help to an extent I suppose.
I have heard that some countries in Europe legislate the age of tires ?
In most cases, I find that pre trip inspections are mostly done in the cab, on paper or on the Qualcomm. It is interesting to watch truckers at a truck stop start their rigs in the morning and drive off... The same goes on the last day of a bus rally where most start it and go as soon as they have enough air to release the brakes.
Sure everything felt good and in good order the day before, so off we go the next morning. We know the rig intimately, so we get lulled into thinking a thorough pre trip isn't necessary. I am guilty of that myself. But one has to pull up their socks and get with it. It is a legal and moral liability to be as diligent as possible.
RJ Long, a veteran professional bus driver, has given seminars on pre trip inspections at bus rallies, and observed bus nuts drive off without even a walk around. I have offered to do pre trip talks at rallies too, but with lack of interest, it doesn't happen.
This is a lot of rambling for nothing that anybody here doesn't know.
The moral of it all is: it is all the driver's responsibility, and liability, to keep his vehicle in good repair, and to drive it safely.
JC
When buses blow tires, bad things happen. Which is why I just finished replacing every single one of my tires. All eight are less than 9 months old. Btw, every crash in every one of these photos had fatalities, and every crash was caused by a tire failure:
(https://uploads.tapatalk-cdn.com/20170517/6005154b47e6b18f72e4fec0d66520fd.jpg)(https://uploads.tapatalk-cdn.com/20170517/01a1fb8ade9aefeffa73a2fccd203f6c.jpg)(https://uploads.tapatalk-cdn.com/20170517/f04b4491f53bc72e8fa7c01d9eead1f4.jpg)(https://uploads.tapatalk-cdn.com/20170517/a7c53168a1e90a0670f7a900ce5885f2.jpg)
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What caused the tire failures? Maybe just bad luck, like hitting a sharp object on the road that blows the tire rapidly. Maybe the tires were marginal in terms of condition, wear, and age at the start of the day. It is up to the driver to decide whether he drives that bus or not given its mechanical condition. But the problem in the trucking and busing industry is the pressure from the employer to keep driving. The driver should refuse to drive a bus with marginal tires, but if he does, he will be promptly replaced by someone who is not as difficult. Have you often seen tour bus drivers walk around their bus to check tires and other things? No, they have a smoke, or talk to other drivers or passengers, assuming that everything is ok with the bus. When I drive charters, staying in hotels, I see other bus drivers in the morning just sitting in their seat filling out paper work while the bus is idling. Some of that paper work is the pre trip form. But I don't see them checking tires with a hammer. They just assume that the tires are fine, because after all, they were fine when they parked the bus the night before. Some of the late model buses have TPMS that would alert a driver of under inflation. But you have to walk around and bend over and feel with your hands to look for cuts and tears, and wear. Some companies are very good at maintenance and encourage drivers to do pre trips and ongoing inspections. Others are much less so, pushing drivers into unsafe situations that can, and do result in accidents.
What's next, you tube videos from 1960 high school driving class to make everyone nauseous?
It is usually safe to preach safety, but not with me, I'm tired of it. We (or me) have heard enough. My bus is safe.
--Geoff
Quote from: windtrader on May 16, 2017, 11:25:03 AM
Obviously, it is vital to have tires that are safe. "Old" or "aged out" tires has no clear specification to define when they are no longer safe. The CHP has vehicle inspection stations along the highways, one goal is ensuring heavy trucks are safe to travel on the road. If the CHP deems a truck road safe, that is a green light for me. Interesting, that the CHP does not check tire dates, only condition. This is from a first hand conversation with an inspection officer at the Fairfield station.
To each their own . . .
I am amazed at the casual concern some have concerning tires.
As Scott has shown, tire failures can leave a significant impact.
Isn't the CHP is the enforcement arm of the litigation part of the government? So, when it comes to my tires, I am placing my trust in what the tire engineer has to say about tire life.
Cause of tire failure are many & complex. Some damage is cumulative, so the tire fails because of something seemingly small . . . . .
A very good friend recently had a steer tire blow. Tire was only 6 years old & always properly maintained/ inflated.
While I visually inspect my tires at every chance I get, I still can't see inside the sidewall. So, I will replace them based on position & age as I deem appropriate.
YMMV
Seems there is lots more to tire rubber compounding than most mortals can comprehend.
I do my best to keep good tires on things but I appreciate the reminders.
Davy
Good discussion and different viewpoints. Pictures of fatal bus crashes can be posted all day long; the problem is unless one reviews the specific incident and investigation it is unknown the true cause why the tire blew out. Observations as posted above could argue that driver inattention, for whatever reason, to perform an adequate inspection prior to starting a journey, was the root cause as the tire likely showed some visible defect or unusual condition warranting a tire change or inflating to correct pressure or ...
I'll state again, I' a noob so have zero miles on the road in a 15 ton motor vehicle but it seems other than some serious road hazard causing a blowout, nearly all other incidents can be headed off by a through walk around and tire pressure check before leaving and every x miles while underway. And no matter what's been done to prevent a tire failure, there is to do if road debris presents itself with insufficient reaction time to maneuver around it to avoid blowing a tire and crashing off the road.
Clifford made the comment a TPMS is not going to prevent all tire issues and I'm wondering now how effective they are in regular service.
How many posts here have said a TPMS prevented a dangerous situation other than to indicate tire pressure is low which would have been determined by a through walk around before starting the journey?
FYI, I read each of the articles associated with the photos. One bus had a tire failure due to age. Another one had tire failure and the article mentioned it had a tire tread depth that violated inspection. The other ones were just listed as tire failure. I wasn't posting the photos to discuss semantics, I just was countering slightly the OP initial post statement that said this and I quote:
"Mostly, failing tires mess up the fender and undercarriage but rarely do buses crash off the road, flip, or otherwise sustain major problems."
I can't agree totally with that statement and the photos I posted were just to support my position. That's all. Not trying to scare anyone into being safety conscious. I don't have seat belts in my bus, so don't put me in that camp lol. But yeah, buses can flip and crash badly from failed tires. You bet.
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I recently spent nearly a week at a seminar that took place at the Michelin facilities in SC. The people that design and build the tires are in lockstep when it comes to the use of old tires. After 7 years they will not even consider the casing safe. I know others on here have previously stated that is because Michelin just wants to sell tires, but throughout the seminar their entire focus was not on selling tires, but making them last for about 700,000 to 900,000 miles and as many as 4 recaps in commercial use.
When we did tire failure forensics it became abundantly clear apart from age the fastest and most common way to have a tire failure is driving at low pressure, and in fact if a tire is run at 20% less pressure than is required for its load, the tire should be carefully inspected for damage before allowing it to be used again. There are many other reasons for tire failures including improper puncture repairs, but the bottom line is you can choose to run on older tires but you better be skilled at handling a sudden tire failure.
All these reasons for tire failure have some merit but one other reason to add to list is speed . Owning a 4104 that travels at comfortable 55 to 60 mph average , I'm running on some pretty old and sidewall cracked tires , I always check them for pressure and heat and at that speed they barley get warm. I just did 1900 miles and the tires were fine the whole time. If you think traveling with a 15 ton machine at 70 to 80 mph is for you then get ready to react quickly if something goes wrong because your going to need to at that speed . I see it with travel and boat trailers all the time, these guys pass me at 75 mph and sure enough down the road there they are sitting with a shredded tire wondering why, I'm sure. Slow down and enjoy the ride especially when you have precious cargo aboard like your family. Like the many warning signs on the highway traveling to Tn.read " IF YOUR IN THAT MUCH OF A RUSH, NEXT TIME LEAVE EARLIER" Nelson
Most important tyre is the steers at 5 years they go to the back to year 7 then they go to the bin
At $200 to $300 cheap safety, age of tyres is your worst enemy blow a back tyre and it makes a mess blow a steer and luck plays a major part you never know could be halfway round a sweeping 60mph corner
In Australia we need a heavy licence and most states have yearly goverment safety checks even private converted buses, with age and illness yearly medical test to maintain your heavy licence that can be down graded to a car only licence
We are speed limited to 60mph/100kph in all truck/bus/motorhomes over 4.5ton and 70mph/110kph on limited signed freeways for cars apart from the Northern Territory with 130kph zones and a 200k stretch unlimited mainly used by world car companys to test in 45d c high speed runs
Tyres here get a beating as we have large amounts of dirt roads as well as some poor potholed main country highways some dirt roads in Western AU, South AU and New South Wales ect have 600+mile dirt main roads that are maintained once or twice a year
So we all have a tendency to check our tyres every stop, just part of the habit driving here and a requirement nothing worse than tyre problem 700 miles from the nearest tyre shop
Love the out back so much space and isolation filled with intersting people
James
And 16 ton of M A N coach that loves dirt roads
Believe me guy's .I am not down playing the importance of good tires ,but even new tires can fail .A coach that belonged to a church in Statesville N C crashed in Tenn. on the way back from a conference I don't remember how many were killed (seems like maybe five)but it is my understanding that this bus had newer tires .Blew a front tire ,jumped the median and hit a tractor/trailer .The driver of the truck was one of the casualty's.
Geoff, your bus is safe, I do believe you, you are a mechanic, and like mine and many others, it is well maintained, with nothing that would upset a DOT officer at a random road check.
But, as you must know, many not so experienced bus nuts just don't know, or care.
I drive charter buses for a couple of companies who are not "tired of safety". The buses go in the shop every 30 days for an inspection. The drivers are trained and retrained to do pre trips and ongoing inspections, and safe defensive driving. It is their culture. Other smaller operators with tighter budgets have much less lofty standards. I wouldn't drive for them. I don't need a job, I do it part time for fun.
JC
The other side of the coin is>>when bus and car collide,, bus wins!!>>>Dan
What is still missing is any rationale if tire age is such a critical safety issue why would the CHP inspection rules not have tire date code checking on their list? Also, it is fair to say the tire lobby has constantly pushed for the date code inspections as that would increase sales (not sure how much) by forcing aged tires off the road. Just does not add up guys.
I'm no tire expert but I still think from my experience and like I said in my reply earlier, I'm running 12r 22.5 old tires with like new tread and at the speeds I'm traveling and keeping an eye on tire pressure so far so good. I think tire companies do have an interest when giving tire advice, why wouldn't they to make a buck. Most of these casualty bus accidents are from commercial companies where time is money and I'm sure they are speeding towards the next job with full loads of people and cargo unlike most of us bus/rv owners . I also think these commercial type truck and bus tires we are running are made to take a lot more punishment than we might give them in the RV world, Just my opinion. Nelson
Interesting article discussing why the transportation board hasn't set an aging standard yet: http://www.tirebusiness.com/article/20140721/ISSUE/307219981/nhtsa-nixes-tire-age-safety-rule
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Quote from: kyle4501 on May 16, 2017, 06:35:50 PM
To each their own . . .
I am amazed at the casual concern some have concerning tires.
As Scott has shown, tire failures can leave a significant impact.
Isn't the CHP is the enforcement arm of the litigation part of the government? So, when it comes to my tires, I am placing my trust in what the tire engineer has to say about tire life.
Cause of tire failure are many & complex. Some damage is cumulative, so the tire fails because of something seemingly small . . . . .
A very good friend recently had a steer tire blow. Tire was only 6 years old & always properly maintained/ inflated.
While I visually inspect my tires at every chance I get, I still can't see inside the sidewall. So, I will replace them based on position & age as I deem appropriate.
YMMV
Seems there is lots more to tire rubber compounding than most mortals can comprehend.
I don't suppose your friend was on I-95 outside of Charleston? There is/was an issue with 95 somewhere in the vicinity? If so, we might share a friend.
Quote from: daddysgirl on May 17, 2017, 02:30:14 PM
I don't suppose your friend was on I-95 outside of Charleston? There is/was an issue with 95 somewhere in the vicinity? If so, we might share a friend.
Nope, he was still in Florida, not too far from home, just starting out on his trip.
Quote from: windtrader on May 17, 2017, 10:13:00 AM
Just does not add up guys.
yeah it does, u just don't seem to want it too.
The DOT concentrates it's inspection $$'s on commercial operators.
News Flash... they don't take 7 years to wear out a tire.
Quote from: windtrader on May 17, 2017, 10:13:00 AM
What is still missing is any rationale if tire age is such a critical safety issue why would the CHP inspection rules not have tire date code checking on their list? Also, it is fair to say the tire lobby has constantly pushed for the date code inspections as that would increase sales (not sure how much) by forcing aged tires off the road. Just does not add up guys.
You are assuming the CHP knows what they are doing . . . . ;)
CHP doesn't make the laws, they just enforce some of them.
The beauty of being non-commercial operators is we are free to do anything we want and there is nobody to inspect us or regulate us. So if we are comfortable driving on old tires we are just as right as those of us that are uncomfortable doing the same thing.
But to use the previously mentioned Statesville church bus as an example there are now 7 or 8 people dead because it was known to have had a blowout. The driver was not an amateur. It was a commercial truck driver with a lot of driving experience so those that think they can take the risk because they know how to drive may be in denial. That bus went from the eastbound lanes of I-40, through a cable barrier, into the rear of a Tahoe killing the rear seat passenger, head on into a west bound semi killing the driver, and then laid over killing some of the people on the bus including the driver and his wife. There was never a mention in any of the reports I saw regarding tire age so it is anyone's guess as to what happened.
Yes new tires have blowouts, but new tires are driven at lower pressures than called for so to justify driving on old tires is like saying it is OK to drive without a seat belt because sometimes you can get trapped in a burning car.
I also think it is foolish to think police officers who do commercial inspections are not very smart. When I was in a Bendix Brake certification class there were not only mechanics in the class, but there were law enforcement officers and accident investigators. They were very well informed and had a deep understanding of commercial vehicles and took the class very seriously. I doubt if anyone could get past them with anything. They don't inspect tires for date code because there are no applicable regulations, but they do inspect for pressures, valve stem caps, tread depth and physical damage so they get it.
OK first off OLD TIRES ARE DANGEROUS! PERIOD!
Yes I know some people have run tires that are 10-15 yrs old and had no problems.
But they are taking huge risks every time they turn the ignition on!
Now for the issue of DOT inspectors.
They are like anyone else and only as good as the training they have received and how well they apply it!
I have driven commercially for a living for 35+ yrs and I can tell you I have seen DOT officers that would make Barney Fife look like Albert Einstein and at the same time some that would make Albert Einstein look like Barney Fife!
I have personally seen a DOT officer miss blatant obvious violations on a truck while stubbornly concentrating on looking for simple and insignificant violations.
I once had found a cracked rim on a pre-trip inspection and had called and found a shop that had a new wheel in-stock and was on my way to get it replaced and got stop by a CHP DOT officer that was doing roadside inspections less than a mile from where I was going on hwy 395.
He wrote me up for that tire being low on pressure but did not say a word about the obvious crack I was staring at.
When I pointed out that the rim was cracked and I was going to the tire shop right down the road to get it fixed and that was the only reason it was low, he threatened to put me out of service for the cracked rim if I didn't sign his ticket for the low tire. He never even went back to the tire/rim in question to look at it. He just wanted to get his citation signed showing he found a problem. It wasn't at all about safety as much as it was the $ for writing an out of stat trucker a ticket! I signed the ticket, took the truck to the tire shop, took pictures before and after they changed the wheel, got them to make duplicate copies of the ticket, and the receipt for the new wheel and labor.
Then I finished my trip and went home. Once home I wrote a letter explaining exactly what happened and sent the copies of the ticket and pictures along with it. Several days later I got a call from the assistant prosecutor for the court asking me what all of it meant.
I told him I was very upset that they wrote me a ticket for something a s minor as a low tire when I told the officer I was going just a mile up the road to get it fixed and had already made an appointment with the shop that he could call and verify if he wanted too. And that even WHEN I POINTED OUT THE CRACKED RIM ALL THE OFFICER CARED ABOUT WAS ME SIGNING THE TICKET HE ALREADY WROTE!
The prosecutor asked so does that mean you intend to fight this ticket?
I told him if he was unwilling to dismiss the ticket and send me proof it was dismissed yes I intended to fight it!
He told me it seemed awful silly to waste all the time and $ to come out and go to court to fight such a little ticket! I told him I didn't care about the $ or the time it was the principal! He told me "See ya in court then, have a nice day!"
So I hired a local attorney who showed up in my behalf and got the judge to dismiss the ticket right away! It cost me $150 to fight a $35 ticket but I was happy!
Another time down on I-8 me and 4 other trucks rolled across the scales in Winterhaven, CA (just outside of Yuma, AZ) and out of the 5 I was the only one pulled in.
As I gathered my paperwork (log book, registration, and bills of lading) that I knew he would be asking for he walked out and told me it'll just be a minute, as he walked on by.
When he came back he had a 6' ladder, a flashlight, and an extendable mirror.
He told me I just want to make sure that you have mufflers in those stacks. (I had 10" stacks on the truck and trust me I bought and put them on the truck and there were no mufflers in them!) I started to admit there was not a muffler in there when he looked in with the mirror and said "yup I see it, you can go, have a good night!"
So again they are only as bright as they wanna be!
;D BK ;D
I drive school busses for work. The dot code on the rear duals on some busses is 4007 indicating week 40 of 2007. Those tires are unlikely to be retreaded. In the view of the work mechanics, they're fine on duals. The steers are what need to be pristine.
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@Nelson - Although the tires on bus conversions and commercial trucks and trailers are the same, the usage pattern is very different. Surely, the tire manufacturers make commercial tires best support commercial use/abuse; busnuts driving old buses are not even on their radar. If busnuts perform regular tire checks before and during trips, I'd be a tire related issue is caused by something other than age.
@Scott - Great link, My followup to your post is in another post.
@Kyle - Tire science and failure analysis are complex subjects, far far beyond my abilities. I can research the work of other reputable organizations and make sense of their findings. Read the following post. California Highway Patrol does enforcement of laws including laws related to safety of commercial trucks. They do not legislate the laws, business, lobbyists, DOT, etc and legislators do. I have zero experience as a professional trucker so I have no idea how long commercial tires keep rolling. I do know commercial tires are engineered to be recapped multiple times, keeping that original casing on the road longer. I do see many stored and dusty trailers and wonder how old those tires may be and whether a trucker hired to haul that trailer will refuse the load due to aged out tires. I'm kind of thinking the trucker will ensure the tires have tread and sidewalls look fine and defect free, then hop in and go. Please see the following post.
@Jon - It is not just busnuts who can drive old tires. As you state, there are age requirements for safety inspections so commercial truckers drive them too. From multiple chats with the CHP and commercial vehicle inspection team, they take safety extremely seriously and are very knowledgeable what a safe truck looks like. A tour operator who I spoke with told me two guys show up and spend all day on ONE coach performing the required inspection. I asked who pays for that, he said it comes out of the various governmental fees and licenses they pay.
It is difficult to make a case giving a specific tire related accident. Please read the full report in the following post. Even the experts and I do mean experts are often unable to identify the true cause of failure.
@BK - With 35+ years of commercial truck driving, I'd argue they did an excellent job as the hundreds of other times, I'm guessing they did not miss a cracked rim. :)
@Zephod - After all the hoopla I create around here, this time on aged tires, I'm thinking the best compromise solution is to have two current newer steers and keep old (aged) tires on the duals and tag, checking them every trip and monitored by TPMS for pressure and temp.
I researched Scott's link. Good start. I contacted the author, Dan Zielinski, Sr VP at the Rubber Manufacturers Association (RMA), the national trade association for tire manufacturers. As their address is K st in DC, obviously a paid lobby group.
From the original article
"The RMA and its members have commented extensively to NHTSA during the long process of tire-aging tests, Mr. Zielinski said during a July 11 conference call on the NHTSA report and other issues. The agency has conducted five separate phases of tire-aging tests since 2002.
"Over time, the agency was not able to articulate, at least to us, what the benefits of a tire-aging rule would be," he said. "They believe tires are performing better than ever, because of the new safety standards.
"I would add that the evolution of tire technology has also played a role, as manufacturers strive to improve tire performance," Mr. Zielinski said.
Meanwhile, the RMA succeeded in getting language added to the newly passed Colorado scrap tire management bill that makes it illegal to sell an "unsafe used tire" in the state, according to Mr. Zielinski. Colorado defines an unsafe used tire as whatever would cause a tire to fail a state safety inspection, he said. "
NHTSA's research on tire aging concluded with a report issued in 2014.
https://www.regulations.gov/document?D=NHTSA-2005-21276-0073 (https://www.regulations.gov/document?D=NHTSA-2005-21276-0073)
Please read it full, it is not that long. Following is a portion for those who do not.
The case for TPMS
Tire aging failures tend to appear in the high heat states, in the summer months,
during the day, while the vehicle is being driven at highway speeds. All of these factors make it
more difficult for the tire to dissipate heat, and heat build-up is the main factor in these types of
failures
The results of this research indicated that there are two mechanisms operating to produce
changes in tire properties. First is degradation of the rubber compound and material interfaces
due to the effects of heat and reaction with oxygen (thermo-oxidative aging). The second is the
effect of cyclic fatigue during tire deformation, which can initiate and propagate cracks and
separations.
In summary, NHTSA's main findings with regard to tire aging can be listed as follows:
• The aging mechanisms that are most likely to affect the relative safety of a tire are
chemical and mechanical in nature. Chemical aging occurs due to the combined
effect of heat and oxygen on the rubber compound and mechanical aging results from
the stresses and strains that a tire incurs during its normal use.
• In the warmer parts of the United States where we have data, including Arizona,
Florida, Texas and Southern California, there appears to be a relationship between the
age of the tire and the propensity of the tire to fail.
• Tire aging failures tend to appear in the high heat states, in the summer months,
during the day, while the vehicle is being driven at highway speeds. All of these
factors make it more difficult for the tire to dissipate heat, and heat build-up is the
main factor in these types of failures.
29
• Artificially aging a tire in a laboratory oven is a scientifically valid method to
accelerate the tire aging process and to simulate a naturally aged tire in service on a
vehicle.
• Our current oven-aging protocol approximates the aging experienced by a tire with
four years of service in Phoenix, Arizona.
• Oven-aged FMVSS No.139-compliant tires developed less severe failure modes
(mostly cracks) than oven-aged pre-FMVSS No.139 tires after endurance and low
pressure test.
VII. CONCLUSIONS
When Congress suggested the idea of a tire aging test requirement, passenger car tires and
light truck tires were regulated under FMVSS No. 109 and FMVSS No. 119 respectively. It was
believed at the time that a tire aging standard would make tires more resistant to degradation.
The agency believes that an improved roadwheel performance of oven-aged FMVSS No. 139-
compliant tires when compared to oven-aged pre-FMVSS No. 139 tires and an overall reduction
of tire-related crashes have lessened the tire aging concerns since the TREAD Act was enacted.
At this time, the agency does not believe it is necessary for motor vehicle safety to add a tire
aging requirement to its light vehicle tire standard due to the following reasons: First, FMVSS
No.139 has contributed to an increased robustness of oven-aged light vehicle tires. Our research
has shown that oven-aged FMVSS No. 139-compliant tires are more resistant to degradation than
oven-aged pre-FMVSS No. 139 tires. Second, light vehicle tires are performing better on the
road as reflected in our most recent crash data. Third, a mandatory TPMS on light vehicle tires
30
since 2007 has helped alert consumers to under-inflation, which is also known to degrade tires
faster.
Tire aging is still a concern for the Sun Belt states, during the summer months when heat
build-up can cause a failure. Spare tires remain a concern as well, since they are not replaced
regularly and may still show enough tread, even though the structural integrity of the tire may be
compromised by aging. Adding to this concern, spare tires are often rotated into use and are sold
as used tires.
For the reasons stated above, the agency is coordinating a promotional and educational
campaign to raise consumer awareness about tire aging issues and how to prevent these types of
failures. Campaign initiatives and outreach efforts to consumers, partners and the automotive
service industry will include social media messages, fact sheets, infographics, and other web
content.
The apparent theme is it is required to have relatively new tires on the steers, but OK to run aged tires on the drives.
I am not familiar with any coaches other than a Prevost, but I know for certain if a drive axle tire lets go the driver still has to exercise good control over the coach. Even if only one of the duals fails the remaining tire also has been ruined because it is now carrying more weight than its air pressure will safely carry. The lucky drivers will retain control and no damage other than a couple of tires will occur. But more often than not a blowout on the drives is going to deeply affect a wallet. It is common for body damage to be a result as the tread begins slapping around before it departs the vehicle. It can and has resulted in the loss of body panels, "fenders", muffler, and side engine doors.
If an inner drive tire comes apart it is not unusual to have air bags or brake chambers or both damaged along with other significant damage to the coach.
It all comes down to a risk versus reward calculation and owner considers when evaluating the risk of running on old possibly dangerous tires. BK has much more experience in this and I hope he offers an opinion.
Thanks for that article Don, I feel better about running older tires now, but I wasn't too worried about it before and like I said running them on my 55 - 60 mph speed demon 4104 helped.
@Nelson - Your welcome.
I'm glad to have gotten pulled down this rat hole, hey, I don't even have the bus to worry about. LOL But most used coaches are running less than new tires, many getting toward that "aged" timezone. This has a bearing on the value of the coach, so that is why it's important for bus buyers to understand this topic and know what you face when buying that coach with "used" tires' Makes a big difference if you can run for some time on 7 year old tires that look nearly brand new vs some 50% tires that are a decade older or more.
Each person forms their own opinion based on different criteria and factors. Anecdotal stories, first person experiences, science based reports, group think, etc. all weigh in on how one forms their own opinion. Obviously, I am fact and expertise based and my opinion is based on industry science tests and reports, conversations with government agencies that make and enforce rules regulating tire usage, and NGO that lobby between government and private sector business related to rubber tires.
I can say that tire age definitely affected the price I was willing to pay for the GMC 5303 that I bought. The cost of 6 new tires is nothing to sneeze at, and if I'm putting my family in a 48 year old coach, a blowout from an old tire is not a risk I'm willing to take.
Quote from: Jon on May 19, 2017, 03:15:06 AM
It all comes down to a risk versus reward calculation and owner considers when evaluating the risk of running on old possibly dangerous tires.
AMEN !
I have seen obviously dangerous wheels / tires on buses at rallys. Upon pointing out the issue (for example nuts full tight, but the rim was loose ! ) , I was told that they didn't feel like it was a problem.
I worked in R&D for a major power transmission company. After running the lab testing & reporting to marketing - you wouldn't believe the spin they would sometimes put on things. That is why I take anything in a report with a grain of sand.
FYI, I have experienced 4 or 5 blowouts. On ALL of them, the tires were purchased new by me & never run low on air. They all looked very good & easily passed visual inspection just prior to failure. The common denominator was age & location. All were over 6 years old and used in South Carolina.
After watching how fast things can go bad after a front tire blowout, I am going very conservative with what I choose as acceptable tire age.
I know these things are not cheap, but it is the way I like to travel.
What ever you choose, I wish y'all safe travels. 8)
Always be prepared for a front blowout. This is one reason school busses are limited to 55mph.
The vast majority of bus crashes are due to driver error. As an example, over the past year the bus I usually drive for work has had the front end wrecked and rebuilt due to one of the other drivers failing to yield. One bus crashed into two other busses at a school when the driver was impatient.
From the crashes at work, speed and impatience are the biggest driver errors. I get criticized by my co driver for my "slow" driving. I drive within the speed limit!
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Quote from: kyle4501 on May 19, 2017, 04:43:04 PM...FYI, I have experienced 4 or 5 blowouts. On ALL of them, the tires were purchased new by me & never run low on air. They all looked very good & easily passed visual inspection just prior to failure. The common denominator was age & location. All were over 6 years old and used in South Carolina. ...
Kyle, have you ever had the circumstances to compare the effects of a bus stored outside versus one that's been in a covered storage most of the tires' lives? There's some experience that says that that makes a difference but most of us haven't had 10 years of both.
Thanks, BH
I have never stored any of my coaches outside. When not in use they are undercover in a closed garage.
I know for sure that compounds are vastly improved from what they were in the early 90's because at 5 or 6 years my tires on my first coach were showing signs of sidewall cracking. I am now replacing my 5/6 year old tires this month and they show no signs of sidewall cracking.
I cannot compare tire life relating to inside or outside storage but I do know the biggest factor impacting tire life is how we use our coaches. If we are not routinely exercising our tires like the commercial operators we are not releasing the compounds in the rubber that fight the effects of aging and that might be the biggest killer of our tires.
What does "releasing the compounds in the rubber that fight the effects of aging" mean?
Aren't those compounds in the rubber already?
That has been mentioned before, but it sounds kind of voodoo to me...
JC
Blah blah blah. If you haven't taken the time to fully read the reports linked to earlier, with all due respect, go to the back of the bus and mumble to yourself. Age related failures are simulated with oven baking in controlled environments. The reports also clearly correlate earlier tire failure when tires are subjected to high ambient operating environments such as AZ and SoCal. The DOT crash statistics bear this out. Please at least get informed on the science then form your own position on where an older tire lands on the list of events most likely to cause bus accidents. I was not sure about this but after this dive into the topic I'm convinced where I stand on the issue.
Quote from: windtrader on May 20, 2017, 12:55:24 PM
Blah blah blah. If you haven't taken the time to fully read the reports linked to earlier, with all due respect, go to the back of the bus and mumble to yourself. Age related failures are simulated with oven baking in controlled environments. The reports also clearly correlate earlier tire failure when tires are subjected to high ambient operating environments such as AZ and SoCal. The DOT crash statistics bear this out. Please at least get informed on the science then form your own position on where an older tire lands on the list of events most likely to cause bus accidents. I was not sure about this but after this dive into the topic I'm convinced where I stand on the issue.
well no need to continue defending it then.
my pizza oven is not the grand outdoors...it never rains in there nor is it covered in rain runoff and salts...etc. etc.
Quote from: Oonrahnjay on May 20, 2017, 05:48:06 AM
Kyle, have you ever had the circumstances to compare the effects of a bus stored outside versus one that's been in a covered storage most of the tires' lives? There's some experience that says that that makes a difference but most of us haven't had 10 years of both.
Thanks, BH
Only if you consider a covered spare tire stored inside a suburban - that one looked brand new, excellent condition. After 1000 miles, it let go with no warning on a clean interstate.
Quote from: Oonrahnjay on May 20, 2017, 05:48:06 AM
Kyle, have you ever had the circumstances to compare the effects of a bus stored outside versus one that's been in a covered storage most of the tires' lives? There's some experience that says that that makes a difference but most of us haven't had 10 years of both.
Thanks, BH
They will rot a lot faster if parked on dirt also!!!
Quote from: windtrader on May 20, 2017, 12:55:24 PM
Blah blah blah. If you haven't taken the time to fully read the reports linked to earlier, with all due respect, go to the back of the bus and mumble to yourself. Age related failures are simulated with oven baking in controlled environments. The reports also clearly correlate earlier tire failure when tires are subjected to high ambient operating environments such as AZ and SoCal. The DOT crash statistics bear this out. Please at least get informed on the science then form your own position on where an older tire lands on the list of events most likely to cause bus accidents. I was not sure about this but after this dive into the topic I'm convinced where I stand on the issue.
Have you ever written those types of reports? I have, lab tests, data collection, statistical analysis, interpretation, etc.
To put so much blind faith in them . . . . . Well, bless your little heart. Isn't that cute.
*scott quietly exits stage left*
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Don exits stage right. ::)
*sits down with a bag of popcorn and some odd tasting off brand cola to watch the show*
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I just remembered that when I was driving for Swift, some of the trailers had an automatic inflation system for the tires to keep them inflated at the correct pressure. There is a little light on the front of the trailer drivers side you can see in the mirror that if it starts blinking, it means the system is pumping too much air because of a leak. A good alternative to TPMS I think. A lot of logging trucks have that in BC on the drives for airing down in the bush, and back up for the highway.
JC