Good Sam Club Open Roads Forum: Class A Motorhomes: Unusual tire wear
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 > Unusual tire wear

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garyemunson

Reno, Nevada

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Posted: 05/26/20 11:26am Link  |  Quote  |  Print  |  Notify Moderator

My experience with a number of Class A gas motorhomes over the decades is that with the alignment set correctly to whatever the specs call for in maximum positive toe in, the RV will track MUCH straighter on rough roads and crosswinds but you will see more wear on the outer edges of the steer tires. Many years ago I complained to a front end shop about the wear on an old "Flying W" Winnie and they took some toe in off. The difference in steering was noticeable and bad. Had it put back to spec and just resigned myself to replacing the fronts sooner in exchange for better tracking.

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south

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Posted: 05/27/20 08:10pm Link  |  Quote  |  Print  |  Notify Moderator

We ahd that happen to our original GC670 Goodyears but not thaat bad.
They said it was because the front endwas too light, they said it was not aligned properly, then the shocks were bad ad so on.
We replaced them with Michelin then new with orange oil in the compound, not sure what good that does but makes me worry about their life.
The tires are steer axle tires with decoupling grooves on both sides of the thread. One wheel and tire took one ounce to balance the other one required no weight atall on road force balancer.
We ahd the front axle straightened in Mo, later trying to cure a wonder problem, and then the factory on chassis alignment or frame fund the right side of rear axle forward about an inch or so from the left side, loosened axle and welded in washers to fix that.
Don't knwo which or in combination was causing the problem,... oh and the rubber bushings in the sway bar were all chewed out.Replaced them with other rubber bushings because they could not locate urethane near the factory. Steers and handles a lot better but I will be putting in new urethane bushings and shocks. 38,000 miles on an 05 Freightliner chassis

spotrot

Indian Rocks Beach, FL

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Posted: 05/27/20 08:47pm Link  |  Quote  |  Print  |  Notify Moderator

Wow, sorry to hear others have had to deal with strange chassis & tire issues too.
Good to hear you're rolling OK now

Wes Tausend

Bismarck, ND

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Posted: 07/12/20 01:24am Link  |  Quote  |  Print  |  Notify Moderator

...

Even though this thread is already aging, I would like to add some comments to it. It is one of the better subjective discussions of tires that I have ever seen in that it contains fairly wide ranging ideas. I think it will make a good future reference source for RV_NET readers.

I know that it is a common belief that tires worn on both the outer edges are always always caused by under-inflation. I would like to question that.

I had recently been researching dual tire pressure equalization systems whereby the dually tire valves are connected together so that each inflates at the same time from one valve port. I seemed to have run across a related wear issue in this.

I read one or more opinions that dually mounted tires will wear unevenly when they are not inflated equally. One of the info sites was http://www.stengelbros.com/truck-and-wheel-parts/cat-eye-tire-pressure-system/. The claim here is that the under-inflated smaller tire will wear more because the larger full tire will "drag" it a bit. A detailed Case Study by Bridgestone is cited.

The thing is, that if that is true, and a single, non-driven tire is over-inflated and the center tread is larger (bulged), shouldn't the main center tread, which certainly has the most traction, also logically drag the lower contact outer edges of the same tire? In this case, the outer edges should wear more than the center when the tire is over-inflated, not under-inflated as is commonly believed. This is exactly what the OP states of such wear in his original post.. "...have been over inflated if anything...".

Even I am not sure about the above "wear" implication, but I like to keep an open mind. One might be able to detect the best inflation by just tediously choosing the tread inflation shape that yields the lowest TPMS temperature reading. Any scrubbing definitely adds heat, but less scrubbing adds less.

I did a fair amount of tire work on passenger, truck and tractors at my job when I was in high school and learned a lot, not necessarily all from older employees. This was back when belted tires first began to appear. From that and experience since, I can say that very few tire shops fully understand what they are doing and "old wives tales" do very much abound, so a healthy grain of salt is advised. This caution also goes for alignment, balance and ball-joint replacement. Shop training is often more sales-tactic than tech-tactic and probably always was.

The odd wear on the outer passenger and inner drivers front steer is probably caused by the necessary chronic drainage crown on both country gravel roads and paved highways. Even on interstates, the RH lane has this same RH downhill crown. All vehicles are then forced to steer slightly uphill while driving straight ahead. This crown is even known to cause the front passenger ball-joints to wear quicker since more weight is also tilted to the front rh steer tire while it jitters along down the road.

The more even additional wear on outer edges of the steer tire is due to side wind and this should actually be detectable by added front tire temps during intermittent windy area's on such days. But the overall wear should still be slightly more on the outer edges because, although both sidewalls roll slightly, greater weight-shift is on the downstream tire in a wind or downhill crown. As an example race cars generally have the camber changed (to lean in) to accommodate turn-traction, a flatter tread contact pattern during turning on the more heavily loaded tire. In such a case, the tire tread is flatter, rather than tucked-under when the sidewall rolls. If tires could just roll ahead on level ground with no side forces, with no tread squirm, they shouldn't wear at all. Of course there is always some tread squirm, even level.

Wes


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CapriRacer

Somewhere in the US

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Posted: 07/13/20 05:41am Link  |  Quote  |  Print  |  Notify Moderator

Wes Tausend wrote:

...I know that it is a common belief that tires worn on both the outer edges are always always caused by under-inflation. I would like to question that......


And you are right to do so.

My experience is that steer tires wear on the shoulders and drive tires wear in the center and that this phenomenon is much stronger than over/under inflation.

Besides, most tire manufacturers are doing what they can to reduce uneven wear - even uneven wear caused by over/under inflation and the steer/drive phenomenon I mentioned above.


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CapriRacer

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