Both of my front tires have these "scallops" in part of the tread. It looks like someone literally took a knife to the tire and cut off chunks of the tread. These are all position tires so they have like rings of treads around the tire. The issue is happening on the second ring of tread in. The tires are not wearing on the edges so I don't think alignment is an issue. Right tire is far worse than the left tire. Any ideas what would cause this?
This is the second set of all position tires in the front that have done this on at least one tire. The current front tires are two or three years old. Two different brands of tires. I want to get any issues fixed before spending another $800 to $1000 on a set of tires. The first set of tires the local tire dealer said the installer put the tires on wrong. It has to be an issue with the bus if this happened twice now.
Worn front end parts probably or you could try a set of steer tires with the anti cupping groves
When it happened to me on other vehicles it was worn out front shocks. At least, the shocks were stock, shot, and the tires didn't cup again after I changed them.
Brian
It's pretty hard to "put the tires on wrong". They mount to the rim only one way. They should be balanced. They bolt to the hub only one way.
There are a number of potential causes. Alignment, low air pressure and worn shocks are probably the most likely, but worn king pins, bearings, spindles and
tie rods could all play a contributing factor. Take it to a front end alignment specialist. There's one in Elk River that has a good reputation, I think.
I ran my air pressure according to the mfg chart for the weight on the axle, and they cupped badly. I increased the pressure on the current
set and so far I'm not seeing any similar wear.
Once it starts, it creates an oscillation that just make it continue to worsen. When you get the problem fixed and replace them, run them on the tag axle
where they will scrub off the wear patterns.
What kind of feedback do you get thru the steering wheel. Any kind of "speed wobble"?
Have you checked out the front end suspension and steering components?
If you are out and about near a scale check the balance weight of your unit. What are the axle weights?
A TPMS system is helpful although a tad expensive but then again tires are cheap ... right?
They mount to the rim only one way...
not true...lots of tires are uni-directional.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.bridgestonetrucktires.com%2Fus_eng%2Freal%2Fmagazines%2F97V1Issue1%2Fimages%2FDrTire.Jpg&hash=b8897ccd79261191371e0d79d791831e4807e029)
Any directional tire will have arrows clearly molded into the sidewall.
Quote from: krank on March 21, 2015, 06:27:51 AM
What kind of feedback do you get thru the steering wheel. Any kind of "speed wobble"?
Have you checked out the front end suspension and steering components?
If you are out and about near a scale check the balance weight of your unit. What are the axle weights?
A TPMS system is helpful although a tad expensive but then again tires are cheap ... right?
No feedback through steering wheel or speed wobble.
Have not checked front end suspension or steering though steering gearbox has been rebuilt and tie rod ends replaced.
Each wheel has been weighed and front wheels are very close in weight.
I have TPMS, but that doesn't help with tire wear unless pressures are way off.
i would suggest that it would need to be something that is pertinent to any axle position, i have had a tire scallop on a tag axle.
i do not think it is a steer problem, probably a suspension or shock problem.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2F%5Burl%3Dhttp%3A%2F%2Fwww.aa1car.com%2Flibrary%2Ftirewear_chart.gif%255Dhttp%3A%2F%2Fwww.aa1car.com%2Flibrary%2Ftirewear_chart.gif%255B%2Furl%255D&hash=c8092355c1d8a4cc611bda88b63d29bc32f2d382)
Quote from: eagle19952 on March 21, 2015, 08:30:12 PM
i would suggest that it would need to be something that is pertinent to any axle position, i have had a tire scallop on a tag axle.
i do not think it is a steer problem, probably a suspension or shock problem.
I had forgotten that this also happened on a tag axle tire in the past. I had this happen to one tire on the front axle and one tire on the tag axle. I moved the one good tire on the front to the tag position when I got new tires in the front.
How hard is it to replace shocks? I'm not sure mine have ever been replaced, but the local bus shop thought they were still good when I got the bus.
If the scallops are on both sides of the bus front tires I would say it is worn front end parts like the king pins or A frame bushings that is a independent axle on each side with A frames upper and lower isn't it ? sorta like a Eagle suspension
Best case would be balancing, but if it's happening on both sides that would seem unlikely. It would seem that you will have to find a good front end shop. They should be able to tell you about any suspension, shock or alignment issues.
Quote from: Lin on March 22, 2015, 04:39:56 PM
Best case would be balancing, but if it's happening on both sides that would seem unlikely. It would seem that you will have to find a good front end shop. They should be able to tell you about any suspension, shock or alignment issues.
I am pretty sure the tires were balanced. This happened on two sets of tires. The steel wheels were replaced with the current set of tires. I wanted to take pictures today, but I haven't felt that great today so I didn't make it out there.
I have taken the bus to the shop in Elk River, MN that Craig mentioned before for steering work and I plan to take it back there to look at this issue too. I was hoping to get over there in the next week or two, but I remembered that spring road load restrictions are in place and the bus is over the limit for some of the roads.
Oh yeah, and how many miles on each of those problem tires?
Brian,
I've had the same issue and have been told the same things these guys are saying. Have your kingpins rebuilt (fun! not) and shocks replaced. I need my kingpins rebuilt and just need to schedule a week at some point in tthe future to make it happen.
-Sean
I had that, replaced shocks and that cured it.
If you're running all position tires without the decupler groove on the side of the tire, around 60,000mi, you'll start to get this kind of tire wear. You should have line haul steer tires on the front if you want to get more than 50 or 60,000 miles out of the tires. Good Luck, TomC
Current set of steer tires has less than 20,000 miles on them. The set before that I got maybe 30,000 miles out of them.
I had a customer with a new Freightliner that had a truck do exactly this. It was cured by a complete all axle alignment. Good Luck, TomC
We found if the rears are out of alignment the steers would wear both on the same side ( both on the curb side usually) and wear off smoothly but not scallop both edges.
I had the rear aligned within the past two years. I don't recall if the front was checked or not at the time.
I finally had a chance to look more closely at the tires on Friday. They aren't as bad as I originally thought. The wear isn't nearly as bad yet as the last set of tires that I had to replace due to this same issue. The tires are probably salvageable if the problem causing the strange wear can be fixed.
I have attached photos of the tires. The problem is on the inside edge of both front tires. I took the picture from a different direction on the driver's side tire.
That is caused by negative camber not shocks it is caused most of the time by worn king pins or upper a frame bushings letting the wheel lean in on the top that may cost you some bucks to remedy
Once the tire has that wear pattern there no stopping it looks like you have spare a set for the tag now
good luck
Ditto on the tire wear memory. Try a simple toe in check with a tape measure. You may find you are toed out. Does it tend to wander or dart one way or the other especially on an asphalt roads?
I talked to JD over at C&J Bus Repair about this today. He has seen this exact issue before and he doesn't think it is king pins. He says the tires are just bad, or it could be toe-in.
I looked through my maintenance manual today and it didn't really clear much up. You would think replacing the king pins is easy if you read the book, but I know it is a long process even for an experienced shop.
Quote from: belfert on March 31, 2015, 05:47:01 PM
He says the tires are just bad,
i have had this happen on tires that were fine and developed scallops with years and miles on them.
the just bad argument makes no sense to me
.
Inside wear I would suspect toe out. No de-coupler grooves don't help but that usually causes outside wear too.
I run 12r22.5's on the front of my highway truck. Nobody makes a 12r with a decoupler so I get that kind of wear on the outside and some on the inside. Lucky to get 100,000 mi out of a set.
It's not king pins as that usually appears as several diagonal bands of wear across the face of the tire. Bad or loose wheel bearings can cause similar wear as king pins.
What size and brand of tire?
Kevin
Kevin-next set, switch to 315/80R-22.5 tires. They are the metric equivalent of the 12R-22.5, but have 18,000lb rating. Many tire manufacturers are making highway steer tires. The 315 is the popular tire in Europe since their axle weights are higher than ours. Most new buses are using the 315 (even 365's) since they are getting heavier. Good Luck, TomC
I sure the heck hope I don't need upper control arm bushings. They are $620 each! I would need four to replace them on both sides.
I finally got the bus in to get this tire issue looked at. The service place did an alignment and found the toe was out by 1/8". The guys at Precision Frame in Elk River, MN thought it was the tire and recommended I go back to the tire dealer. The tire dealer said it is not the tire. He pulled out a book and showed me a picture of the exact problem I am having. The book said low tire pressures and bad shocks are two possible causes. I said I run the proper tire pressures by weight. The tire guy still recommended increasing the pressure.
Nobody said there is any problem running the tire for now. They did recommend swapping the left and right tires. I will get new steer tires in a year or two and swap the current steer tires back to the tags axle. i will probably replace front shocks since they are fairly inexpensive.
I know from experience if you put scalloped tires from the steer to the tag the tag position will eat them up in a relatively short period of time. The best place for tires with that issue will be on the drive and over time the drive axle will get them wearing evenly.
I had one tire scallop on a bogey...in 100 miles at 110 psi...shocks are IMO, what caused it...and maybe age as the tire is close to out dated..
Brian I believe you driving to close to the Ocean, and that's why you are getting Scallops, little butter and white wine done. ;D