We are running Firestone FS400 (315/80R22.5) on our 4108. They came on the bus and since they're in great shape we are running them for now. I know that they are more tire than we need.
Weighed the coach this weekend with full tanks all around and a typical load of stuff. Only thing missing was the two of use in our seats, and together we done make 350 pounds.
Steer axle: 11120 (approx. 5560 each front wheel)
Drive axle: 18460 (approx. 4615 each rear wheel)
TOTAL: 29580
Chart from Firestone shows the following:
Dual: 5575/80psi 5840/85psi 6070/90psi 6395/95psi
Sing: 6175/80psi 6415/85psi 6670/90psi 6940/95psi
I have been running 95psi all around, but it appears my math was off. Thinking of dropping to 90psi in front and 85psi in rear to bring things closer to the chart but still allow for a good safety buffer above the minimum. My thought is that this will give a softer ride.
Any thoughts? Is the difference going to be noticeable enough to be worth the effort?
Changing the air pressure from 90 to 105 didn't make any difference in ride. However, changing the shocks out to what was supposed to be there made a very noticeable improvement !
I like having my tires at the max sidewall pressure. That way, when there is a leak, I'll have more time to catch it before it drops low enough to cause damage.
I also use CrossFires on the duals to ensure both tires are carrying the load equally.
Added on edit -
BTW, I've experienced tire failures while driving - My choice is to do as much as I can to prevent that ever happening again.
If ride quality is so bad that you need to lower the tire pressure to minimum levels, you might want to consider a good tire pressure monitoring system. . . .
Heck I would drop to 80psi all around. You're still above at the psi.
??? ??? ??? ??? ??? ???
but, 92 psi is not enough...it has been said ;D
LOL if ride is what you after buy a Eagle :P
Too many issues with rust falling off and causing leaks in rear tires from running over it.
Quote from: chessie4905 on May 29, 2018, 04:55:22 PM
Too many issues with rust falling off and causing leaks in rear tires from running over it.
so, be happy in a Bouncy Bellowed Betty :)
Bouncy? Have you ever ridden or driven a GMC? The older models would rock side to side some.
Quote from: chessie4905 on May 29, 2018, 05:36:33 PM
Bouncy? Have you ever ridden or driven a GMC? The older models would rock side to side some.
did you mean roll u out of bed ?
I couldn't reach steering wheel and pedals from the bed, so I wouldn't know. My 4905 doesn't rock and neither did out 4104. Both had rear sway bars. Neither rusted, or broke belts or had drop boxes or had tags.☺
All buses rust even GM's
We ran close to max rated pressure in our tires, when we got to our destination over 5000 miles away, we reduced the pressure to what the tire chart showed for the actual load (similar to Richards #s) the difference in comfort was quite impressive - wished we knew better from the beginning.
Now we're in the market to replace the shocks - these observations weren't focused on until running nasty far north roads (frost heaves, loose gravel, pot holes, etc.)
Our 1953 GM bus has no rust :-)...
LOL oh yea it will have rust on the roof brows just dig around
Its more about tire wear than comfort. Full pressure and no weight leads to poor wearing tires, plus a hard ride, let alone road "sticking" power. You need to ride on the full foot print of the tread, not just the high centers of your tires. Why do you think they have charts with the proper pressures?
Last I checked, aluminum roof brows don't have a tendency to rust much. At least in a GM, most rust can be seen, not hidden in the walls. I would not buy an MCI or Eagle unless it was a later model with stainless wall ribs. Well, to be honest, the only one I would buy would be a later Prevost.
When did GM start using aluminum roof brows ?,Prevost rust too they have a lot of steel in those ,buses don't use S/S in high stress areas like the engine compartment and other places and from the belt line up they are steel lol most buses use the Eagle frame design now.
Back to our normal programing tire pressure all the tour operators like my friends at Arrow (300 buses) and GreyHound run strictly by the data plate provided by the manufacture,the radial tire design air pressure doesn't affect the foot print if kept in the maximum and minimum range.
Regardless of the charts tire manufactures will tell you a fully inflated tire will wear and last longer, truckers never adjust the pressure on their tires for weight when installed it is what it is and they get over 100,000 from a set . Add a little 15/40 engine oil that could help
I was going by the weight/pressure chart, but tire shop said those pressures are too low. I was only running 75 PSI in some tires. I now run them all at 95 PSI.
I had a tire blow the sidewall last year and the tire shop said it may have been caused in part but the low pressure.
This is beginning to sound like another "what oil should I run in my engine" thread!
:o ::)
Quote from: chessie4905 on May 29, 2018, 04:55:22 PM
Too many issues with rust falling off and causing leaks in rear tires from running over it.
5000 Comedians out of work and this guy is trying to be funny. ;D ;D ;D
Eagles don't rust...much! :-)
Quote from: belfert on May 30, 2018, 06:27:41 AM
I was going by the weight/pressure chart, but tire shop said those pressures are too low. I was only running 75 PSI in some tires. I now run them all at 95 PSI.
I had a tire blow the sidewall last year and the tire shop said it may have been caused in part but the low pressure.
Your tire shop isnt going to know better than the manufacturer.
Quote from: opus on May 30, 2018, 12:03:43 PM
Your tire shop isnt going to know better than the manufacturer.
I would agree. The tire manufacturer is the one that is supplying the warranty and thus footing the bill for claims, not the tire jocky.
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At least this is an easy fix. I'll be lowering the pressure all around to more closely match the chart, of course with a little bit of a buffer for all the crap that will end up on the bus by the end of the summer.
Quote from: thomasinnv on May 30, 2018, 12:44:33 PM
I would agree. The tire manufacturer is the one that is supplying the warranty and thus footing the bill for claims, not the tire jocky.
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you guys are funny every Michelin tire I ever tried to get warranted they all tell me wrong air pressure (low) caused the tire to blow.
Quote from: luvrbus on May 30, 2018, 01:23:30 PM
you guys are funny every Michelin tire I ever tried to get warranted they all tell me wrong air pressure (low) caused the tire to blow.
Honestly, I've never tried to warranty a tire accept a few that were under a road hazard warranty, but that is thru the tire shop and not the manufacturer. I don't imagine it's any easy task trying to get ANY tire manufacturer to accept responsibility and warranty a tire.
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Your in house warranties are better than a manufactures warranty anytime,Discount Tire is the only place I can find that will warranty trailer tires but they charge 10 bucks more a tire and worth it no questions asked
Quote from: luvrbus on May 30, 2018, 01:35:44 PM
Your in house warranties are better than a manufactures warranty anytime,Discount Tire is the only place I can find that will warranty trailer tires but they charge 10 bucks more a tire and worth it no questions asked
Walmart does road hazard for 10 ea but I don't know if that applies to trailer tires. Last set of trailer tires I got at discount tire, and I did get the road hazard on them. Turkies tried to charge me for putting in nitrogen which i never asked for. I said you need to take that off the bill, he said but the nitrogen is already in there. I said take it out then. He left it alone and took it off the bill lol.
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Quote from: RJ on May 30, 2018, 11:43:06 AM
This is beginning to sound like another "what oil should I run in my engine" thread!
:o ::)
Always interesting to see how different people interpret the information.
- I used to think the manufacturer's recommendation to replace tires at 5 to 6 years was just to sell more tires - then I experienced first hand several age related failures.
- I have also run the lab tests & seen how that compares to the real world data -AND- then there is what marketing published as results.
Bottom line - gather as much information as you can & make the best decision you can for your needs.
Everyone should take timeout and visit the proving test grounds for tires,I been to Michelin in SC,Cooper outside of San Antonio,BridgeStone in west Texas,1 in Yuma for Toyo and the old Ford testing grounds in Yucca Flats not far from me.The last time I was at Yucca they were testing motor cycle tires that job they can keep lol most of us have 8 tires no way would I test motor cycle tires
It amazes me the torture they do to a tire to try and destroy a tire at those places
I've been digging around on our same old GMC since April of 1979 & I'm honestly saying that there is no rust on the old girl, that's my story & I'm stickin' to it... :-)
Quote from: luvrbus on May 30, 2018, 05:24:54 PM
Everyone should take timeout and visit the proving test grounds for tires,I been to Michelin in SC,Cooper outside of San Antonio,BridgeStone in west Texas,1 in Yuma for Toyo and the old Ford testing grounds in Yucca Flats not far from me.The last time I was at Yucca they were testing motor cycle tires that job they can keep lol most of us have 8 tires no way would I test motor cycle tires
It amazes me the torture they do to a tire to try and destroy a tire at those places
When I had a motorcycle shop...my insurance wold not let me sell or touch tires.
You got to sell a lot of tires to cover that nut.
Quote from: RJ on May 30, 2018, 11:43:06 AM
This is beginning to sound like another "what oil should I run in my engine" thread!
:o ::)
All oils are the same right? :o
Yes unless you pull a lot of hills then they are different, except when the batteries are connected in Parallel or are obtuse! :o ;D