Strange tire wear on TAG tires

[CCMH]

So after rubbing my hands around the edges of my tires today just checking for wear differences, I found one. Glad I was checking...

It seems my tag axle tires, both of them by the way, are wearing "roundish" around the edges. Unlike the rest of the tires on the bus. Tires have 8,000 miles on them, and just noticed this. Checked the air and the driver side tag tire had about 85lb's of pressure. Will be watching that tire to be sure, however, the passenger side tire was wearing the same... kinda roundish on the edges.

Is this normal for our buses? All of the other tires are wearing flat and sharp on the edges.

Any experience with this kind of wear would be greatly appreciated. Could this be from suspension issues? Chime in one and all. :)

So appreciative of this group!

[rahangman]

Sounds like a low pressure event....I keep my right at 100

[treedoc]

Curtis You definitly don't have enough tire pressure. A tire on a car, truck or what ever will do the same thing because of low tire pressure. Rick

[Jon Wehrenberg]

Michelin publishes a chart with the correct pressures for the weight carried by the tires. I strongly disagree with those who are of the opinion different pressures will solve the problem.

http://www.michelintruck.com/michelintruck/tires-retreads/load-inflation-tables.jsp

Assuming you have the proper pressures then I would make certain the tires are balanced and the tag axle is aligned correctly.

A tag axle will eat up a tire faster than any other position on the coach once a tire starts to exhibit an unusual wear pattern. When you have the alignment checked, and the tires balanced I would suggest you move them to the drive axle which tends to correct uneven wear.

[LNDYCHT]

Low air pressure is definitely an issue. If you do a lot of tight corners and maneuvering this will also add to this wear. There is more load on the drive axle, so the coach will tend to pivot on the drive axle making the tag axle tires slide as you turn. Low air pressure lets the tire roll over wearin the outside more rapidly. That is why it is easier to maneuver with the tag raised. I would expect to see some scuffing wear on tag tires.

[Jon Wehrenberg]

Depending on how the coach was ordered it may have the system that automatically dumps tag air in sharp turns.

That is invisible to the driver but as soon as the steering reaches full travel in one direction or the other tag air is exhausted and as soon as the steering centers the air bags for the tag axle are re-inflated. Some coaches (Jim C's, Hector's, Michael's and mine) have "stabilizators" (Prevost's term) which are hydraulic cylinders that come into play to keep the rear from dropping when tag air is dumped using the automatic feature.

I have zero unusual wear on my current coach and none on the previous coach and only raised the tag when negotiating extremely tight roads such as in a campground.

If Curtis wants to verify he has the automatic tag dump system he need only drop the front bumper and look up at the steering arm. It will have a stainless steel piece that acts as a cam to actuate a lever operated microswitch. That switch is what causes the dumping of tag air.

[truk4u]

Curtis,

Jon is dead on, forget suggestions to add air before actually weighing the bus and deciding the correct pressure based on the Michelin chart. Once you have that sorted out, then you can look for other causes assuming your pressure is close.

[gmcbuffalo]

Another article on tire use and wear.
http://www.todaystrucking.com/images/MichelinServiceManual2006.pdf

I had the same problem and everything I could find boiled down to under inflation. I had the bus aligned and it came out ok. so I was left with the underinflation theroy.

I have since replaced the tire and will be watching them.

Greg

[jack14r]

The tags take a beating,I am of the opinion that only enough air pressure by the chart is not enough for all situations,weight shifts when we brake,accelerate,corner or when the grade changes.I have seen tags that are scalloped and I also think that too little air pressure is part of the problem,I never set the air pressure on any tire below 100 PSI and I always use 115 on the steer which is higher than the chart calls for.

[Reagan Sirmons]

Jon, I noticed you use your tag sparringly according to your comment. Talk to me about that. I am inclined to use the tag freely yet I do stop when I am putting it back down. I would appreciate comments on this.
Thank you.
Pres

[Jon Wehrenberg]

I am not a tire expert, but have driven around 250,000 to 300,000 on our coaches.

I have to be in a place that involves a very sharp turn before I even think about lifting my tag axle. And then the only reason for doing so is not because I am thinking about tire wear or scuffing, but because I want to shorten my wheelbase by a little to help make the turn. I have always used the Michelin specified pressures plus 5 pounds. The tags on my first coach therefore were at 75 PSI and the current tags are at 90 PSI.

The tags have not shown unusual wear. I made the mistake on the first coach of putting the steer tires that had scallops around the edges on the tag thinking that was a good spot. 5000 miles later the scallops had grown to such an extent the steel belts were showing. Now uneven tires go on the drive.

Very few miles are spent making sharp turns on our coaches. And when I do sharp turns I am going slow so while I am sure I am scuffing the tags sideways they are also rolling so the scuffing is uniform. Ditto with left and right turns being equal in number so I am an equal opportunity scuffer. I have put about 85,000 on this coach since I got it and the tires on the tag were steers new when I got the coach. They have been on the tag position for about 30,000 of their life of 85,000 and when I run my hand across them I feel no irregular wear. But remember, on this coach my tag dumps air when I make very sharp turns, it just does not lift the tag.

On the previous coach the oldest tires had 130,000 on them, but I also rotated the tires on that coach every 30,000 miles. That coach was the one with scalloped tires and an alignment or the use of Equal made that problem go away. I just don't know which was the reason my tire wear issue never reappeared.

[CCMH]

Thanks everyone for all the info. Plan of action is as follows...

Going to take the coach in for tire balancing/equal, and check the valve stems and replace with extensions necessary that will fit new TPMS (Pressure Pro). Swich out tags with outside drive axle tires. Have all tires aired up to 100psi, then weigh the coach. Will then air up to desired pressure. Should know if this has solved the problem within 5000 miles or sooner. If problem persists, will then take a look at the tag alignment and air release/fill for the tag axle.

Wish me luck! :)

[charlesebrownjr]

I notice you said ballancing/equal, make sure you can use the pressure pro transmitters with tires useing equal. I had equal in my last set and when I got my new tires, I had them ballanced by Prevost with wheel weights.

[Prevost1111]

Curtis, I found the exact same problem. I am very careful about air pressure and always keep 105 in the tag. I found this wear just a few weeks ago when getting an engine service at Prevost nashville. The even thought the wear was strange and the tech told me he has never seen that kind of wear. I am getting the same wear on the drive side tag and the passenger tag. Anything you find out please let me know

[AmeriStar]

This is a classic low pressure decription of wear. I would increase the tag pressure to a minimum of 100, and increase the drives and steer accordingly. I'm curious, what brand of tire do you own? Michelin, Firestone and BF Goodrich are notorious for heavy shoulder wear when under inflated. Bandag has receiently developed a 'scuff resistant' retread compound that we have had really good success with. Perhaps when your wear reaches replacement level, you might consider having your tags recapped.