So after purchasing 5 new 37 inch Goodyear MTR's I had a bad steering wheel shimmy between 45-55 mph. (It wasn't there with my 35 inch KM2's the day before)

I took the tires back to get re-balanced, and the shop said they were fine and the shimmy was normal.

I wouldn't go as far as to call it "death wobble" but the shimmy was bad enough at times to be forced to slow down.

After checking the allignment, steering, and johnny joints it was still there

So my son helped me rotate the tires to see if there would be an improvement... nope


I took the tires to another shop to get re-balanced.

They said that two of my tires (on the front) failed the Road Force test, and to take the tires back for exchange.

After arguing with the store manager, I got both tires replaced.

Has anyone else had this problem with the new MTR's or any other tire?

What is different about the Road Force test when compared to other tire balancers?

 

A roadforce test doesnt just spin the tire, it puts a load on it while rotating. On a larger tire any internal defect such as belt misalignment, molding defects can cause a much more exagerated and noticable woble than on say a pasenger car. That doesnt neccassarily mean the tire is bad per se, but if it cant be balanced out then it is good to try and get them replaced because they realy isnt any means to get rid of the vibration/wobble. On a trail only rig it wouldnt be an issue and the tire would probably hold up as long as any other, but on a daily driven rig a bad vibration can not only be annoying and dangerous, but can lead to premature wear of other parts.

 

He summed it up. Depends on how many pounds of road force is on that wheel and tire. Can show you problems for sure. Glad to hear you got that straightened out.

 

The original shop argued that one of the tires in question spun "smooth as glass" on their non-roadforce machine.

So does the roadforce check both out-of-round condition and internal defects?

 

You have to understand that a tire will behave differently under load than not under load. The "shop" in question may be absolutley right that the tire spun true on their machine. But when you spin the tire under load (roadforce type machine) it can show aditional defects. Tires are not just molded pieces of rubber, actually only the tread portion is molded at all. A tire is constructed by layering materials (rubber, steel, kevlar, etc) on a form, then a thick rubber "sheet" is wrapped around it and the whole carcass is stuck in a mold. The problem comes in when some of those internal layers, usually the steel or kevlar, are not aligned properly. YOu cant really see that on a regular machine cause the weight may be fine, but when you place a load on the tire those missalignments will cause the tire to rotate badly, or "wobble". Its a common misconception that tires only vibrate because they have "heavy spots". I tire can be perfectly true weight wise and still wobble uner load which is why the industry is slowly switching to the roadforce machines. The biggest issue comes in the size of the tire, all tires suffer these issues, but on a passenger car (i.e. 195/60R15) it is hardly noticable, but as the tire size grows such as your 35"s it becomes much more exagerated.