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Southsider
New Member

4 Posts

Posted - 08/08/2013 :  05:47:14 AM  Show Profile  Visit Southsider's Homepage  Reply with Quote
Does anyone have a good tire wear pattern guide? We have a new C2 with about 25K on it that has cut down every other row of lugs around both tires on the left rear. We keep 100psi. The bus is used mainly for route. Thanks.

Farmridge
Senior Member

51 Posts

Posted - 08/08/2013 :  06:54:19 AM  Show Profile  Reply with Quote
I don't have a guide, but have you checked the lug nut torque, wheel bearing play, damage to the tires, spring bushings and axle alignment?

If you can't handle the answer, don't ask the question
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bwest
Administrator

United States
2356 Posts

Posted - 08/08/2013 :  07:53:22 AM  Show Profile  Reply with Quote
I would lean toward a pulled or broken cord.

Bryan
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Fastback
Top Member

998 Posts

Posted - 08/08/2013 :  12:45:36 PM  Show Profile  Reply with Quote
I would probably check the wheel bearing adjustment and switch the worn tires to the other side of the bus and monitor.
My guide blames that kind of wear on "tread block/lug wiggle". As causes, it lists inflation problems, loose wheel bearings and some tire designs that are just more prone to that kind of wear than others.
They also define "inflation problems as always a combination of load and air pressure. Too much load and too little air OR too much air and too little load, one way or the other and you have a problem."

Why yes, the ORIGinal CHARGER is a Fastback
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baptistbusman1
Senior Member

USA
76 Posts

Posted - 08/08/2013 :  1:57:52 PM  Show Profile  Reply with Quote
We started running our C2 rear tires at 85-90 psi and it has helped a lot with this problem.

I was formally Baptistbusman. However, I lost my password, and had not updated my email address.

Here is a link to my old posts. http://www.schoolbusfleet.com/forum/search.asp?mode=DoIt&MEMBER_ID=1846
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JustinB
Advanced Member

United States
490 Posts

Posted - 08/08/2013 :  2:34:46 PM  Show Profile  Reply with Quote
Under laoded/overinflated for the rateing of the tire. Rides on the center of the tread wile th open shoulder scuffs along.

I may not know the answer but I can usually find who does.
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bwest
Administrator

United States
2356 Posts

Posted - 08/08/2013 :  7:22:16 PM  Show Profile  Reply with Quote
quote:
Originally posted by baptistbusman1

We started running our C2 rear tires at 85-90 psi and it has helped a lot with this problem.



You think the wear on every other lug on the inside dual can be alleviated with lower pressure? I think someone else was talking a lower pressure too. Haven't had a chance to check the chart I printed off from Firestone yet.

Bryan
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Fastback
Top Member

998 Posts

Posted - 08/09/2013 :  06:26:56 AM  Show Profile  Reply with Quote
quote:
Originally posted by JustinB

Under laoded/overinflated for the rateing of the tire. Rides on the center of the tread wile th open shoulder scuffs along.



Makes sense to me. My tire dealer once accidently mounted a low profile tire on one of our outside duals, the smaller diameter low pro tire wore at a very accellerated rate as it scuffed along with its tread doing more revs per mile than its 11R dual mate.

Why yes, the ORIGinal CHARGER is a Fastback
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bwest
Administrator

United States
2356 Posts

Posted - 08/09/2013 :  11:54:21 AM  Show Profile  Reply with Quote
quote:
Originally posted by Fastback

quote:
Originally posted by JustinB

Under laoded/overinflated for the rateing of the tire. Rides on the center of the tread wile th open shoulder scuffs along.



Makes sense to me. My tire dealer once accidently mounted a low profile tire on one of our outside duals, the smaller diameter low pro tire wore at a very accellerated rate as it scuffed along with its tread doing more revs per mile than its 11R dual mate.



The scuffing I buy, but more revs per mile? How can that be?

Bryan
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Fastback
Top Member

998 Posts

Posted - 08/09/2013 :  12:16:38 PM  Show Profile  Reply with Quote
quote:
Originally posted by bwest

quote:
Originally posted by Fastback

quote:
Originally posted by JustinB

Under laoded/overinflated for the rateing of the tire. Rides on the center of the tread wile th open shoulder scuffs along.



Makes sense to me. My tire dealer once accidently mounted a low profile tire on one of our outside duals, the smaller diameter low pro tire wore at a very accellerated rate as it scuffed along with its tread doing more revs per mile than its 11R dual mate.




The scuffing I buy, but more revs per mile? How can that be?



Think about it, a smaller diameter tire has to make more revolutions per mile than a larger one, its why changing tire sizes effects speedo accuracy.
In our case it was an 11R-22.5" = 504 revs per mile paired with a 275/80R22.5" which does 519 revs per mile. Revs per mile for these tire sizes is from a Michelin truck tire data book.

Why yes, the ORIGinal CHARGER is a Fastback

Edited by - Fastback on 08/09/2013 12:26:24 PM
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bwest
Administrator

United States
2356 Posts

Posted - 08/09/2013 :  2:32:24 PM  Show Profile  Reply with Quote
OK, I understand that. But if the larger one is bolted to the smaller one they are going to make the same revs as the larger one. No?

Bryan
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JustinB
Advanced Member

United States
490 Posts

Posted - 08/09/2013 :  2:36:11 PM  Show Profile  Reply with Quote
quote:
Originally posted by bwest

OK, I understand that. But if the larger one is bolted to the smaller one they are going to make the same revs as the larger one. No?


The larger one will simply attempt to wear down to the same radius as the smaller one.... if it doesn't have catastrophic failure from the resulting heat build-up from being over loaded.

I may not know the answer but I can usually find who does.
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bwest
Administrator

United States
2356 Posts

Posted - 08/09/2013 :  3:52:16 PM  Show Profile  Reply with Quote
Lol, this is just all coffee shop talk anyway and we're not going to get anywhere. Is there anything I can do about the wear I'm seeing on the inside duals that look like what the original poster is talking about? Not all the way across just on the inside lug.

Bryan
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JustinB
Advanced Member

United States
490 Posts

Posted - 08/10/2013 :  08:22:58 AM  Show Profile  Reply with Quote
Get a decent estimate of the maximum load to the gound that axle is putting down. I know that this is a bit prblematic with diminishing loads of live lumber, but try to get close
Consult your tire manufactureer's tire PSI for max loaded radius chart.

Check out an example load and pressure chart here:
http://www.michelintruck.com/michelintruck/tires-retreads/tireInfo.do?tread=XDE M/S

Also check out your:
- Drive axle torque arm and brackets for looseness and torque settings
.....this regular maintenance that is rather critical the first couple of years
- steer and drive axle u-bolt clamp kits for component movement and torque settings
.....this regular maintenance that is rather critical the first couple of years
- Axle alignmeent
- Steer tire toe settings

I may not know the answer but I can usually find who does.

Edited by - JustinB on 08/10/2013 08:25:21 AM
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Tb4020
Senior Member

United States
65 Posts

Posted - 08/12/2013 :  05:48:15 AM  Show Profile  Reply with Quote
Ever follow one down a crowned road? Sometimes the outside duals are hardly touching the ground, we run a lot of dirt roads that are narrow and crowned the insides do wear faster. We try and swap them around but then the drivers see that outside edge worn down and complain that the tires are shot then want to argue about it! Lots of times I'll put a new set of four on and send the worn ones for casings and keep the two outsides until I get a set of four to put on a spare to run them out. Considered going to a closed shoulder drive but the cost was signifigantly higher.
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Fastback
Top Member

998 Posts

Posted - 08/12/2013 :  06:37:05 AM  Show Profile  Reply with Quote
quote:
Originally posted by JustinB

quote:
Originally posted by bwest

OK, I understand that. But if the larger one is bolted to the smaller one they are going to make the same revs as the larger one. No?


The larger one will simply attempt to wear down to the same radius as the smaller one.... if it doesn't have catastrophic failure from the resulting heat build-up from being over loaded.



Won't speculate on the heat build up from over load but the reality is its the smaller diameter tire that ends up scuffing its tread off in this situation. The larger tire will never wear down to the smaller tires diameter as its the one "calling the shots" as far as revolutions per mile.

Why yes, the ORIGinal CHARGER is a Fastback
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Fastback
Top Member

998 Posts

Posted - 08/12/2013 :  06:44:20 AM  Show Profile  Reply with Quote
quote:
Originally posted by bwest

OK, I understand that. But if the larger one is bolted to the smaller one they are going to make the same revs as the larger one. No?




Thats the problem! The only way the smaller diameter tires tread can make the same number of revolutions per mile as the larger one is if it skids the road surface.

Why yes, the ORIGinal CHARGER is a Fastback
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bwest
Administrator

United States
2356 Posts

Posted - 08/13/2013 :  11:34:31 AM  Show Profile  Reply with Quote
quote:
Originally posted by Fastback

quote:
Originally posted by bwest

OK, I understand that. But if the larger one is bolted to the smaller one they are going to make the same revs as the larger one. No?




Thats the problem! The only way the smaller diameter tires tread can make the same number of revolutions per mile as the larger one is if it skids the road surface.



Got it! We were thinking the same things but couldn't tell each other. lol

Bryan
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Fastback
Top Member

998 Posts

Posted - 08/14/2013 :  07:57:40 AM  Show Profile  Reply with Quote
quote:
Originally posted by bwest

quote:
Originally posted by Fastback

quote:
Originally posted by bwest

OK, I understand that. But if the larger one is bolted to the smaller one they are going to make the same revs as the larger one. No?




Thats the problem! The only way the smaller diameter tires tread can make the same number of revolutions per mile as the larger one is if it skids the road surface.



Got it! We were thinking the same things but couldn't tell each other. lol



Darn keyboards anyway

Why yes, the ORIGinal CHARGER is a Fastback
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partsman_ba
Administrator

United States
294 Posts

Posted - 08/15/2013 :  07:02:24 AM  Show Profile  Reply with Quote
Southsider, by any chance are these different tires than you have on your other buses? We had a problem when our director spec'ed Michelin XDE M/S tires - got horrendous outer lug stair-stepping, to the point we had to cross-rotate the tires every oil service. Our normal tire is a XDN2, or caps with 167 tread, which we have no problems with.
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bwest
Administrator

United States
2356 Posts

Posted - 08/15/2013 :  07:38:52 AM  Show Profile  Reply with Quote
quote:
Originally posted by partsman_ba

Southsider, by any chance are these different tires than you have on your other buses? We had a problem when our director spec'ed Michelin XDE M/S tires - got horrendous outer lug stair-stepping, to the point we had to cross-rotate the tires every oil service. Our normal tire is a XDN2, or caps with 167 tread, which we have no problems with.



That's interesting. How do the XDN2 tires do in the snow?

Bryan
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Southsider
New Member

4 Posts

Posted - 08/15/2013 :  08:22:46 AM  Show Profile  Visit Southsider's Homepage  Reply with Quote
As a matter of fact they are Michelin XDE M/S! Stair stepping is a very good description of the problem. I have noticed this on other brands also, but not as soon or as severe as on this bus. I was intrigued by the thought of over inflation being the cause. This bus runs fairly light loads. Just wondering?
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partsman_ba
Administrator

United States
294 Posts

Posted - 08/15/2013 :  12:49:58 PM  Show Profile  Reply with Quote
quote:
Originally posted by bwest

quote:
Originally posted by partsman_ba

Southsider, by any chance are these different tires than you have on your other buses? We had a problem when our director spec'ed Michelin XDE M/S tires - got horrendous outer lug stair-stepping, to the point we had to cross-rotate the tires every oil service. Our normal tire is a XDN2, or caps with 167 tread, which we have no problems with.



That's interesting. How do the XDN2 tires do in the snow?



Well, we're in Eugene, OR, where it snows about once a year, and we have OnSpot chains on the buses, so I don't have a good answer for you. Maybe someone else here has a better answer?
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partsman_ba
Administrator

United States
294 Posts

Posted - 08/15/2013 :  12:56:10 PM  Show Profile  Reply with Quote
quote:
Originally posted by Southsider

As a matter of fact they are Michelin XDE M/S! Stair stepping is a very good description of the problem. I have noticed this on other brands also, but not as soon or as severe as on this bus. I was intrigued by the thought of over inflation being the cause. This bus runs fairly light loads. Just wondering?



I think it has to do with the tire not liking all the turning a school bus does. Funny - I just checked Michelin's website and it states under "Features and Benefits":

Outstanding resistance against the effects of scrubbing - in standard LRG sizes. Resistance to chipping and cutting in LRH sizes with a "*" designation through the use of application specific compounds.

However, under "Specifications", it only shows load range H available (which is what we run no matter what tire it is.)
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