Tire cupping, what causes this?

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I've seen tire cupping on bikes and cars and don't know what causes it.

Shocks, fork oil, tire pressure, voodoo dolls, will sometimes help but it's just a black box to me.

My wife's '95 Exploder cups the front tires (inside edge) and no one can figure it out.

Any ideas?
 
This is a common problem with Ford's "Twin I-beam & Twin Traction-beam" suspensions. This is also a common problem with 4x4 vehicles.

I'm not really sure what causes it. I just deal with it and keep my tires rotated.
 
I agree with Medic, chronic 4X4 problem, could be related to any of a number of things, or combination. Misalignment, out of balance tires, loose front end part(s), or bad shocks. I have had similar cupping on most of my 4X4's, three toyota PU's, Scout. Usually occurs only after 20K-40K on a new set of tires. So hard to keep track of without close observation.
 
I've been told by a few tire guys that it is due to a harmonic vibration that sets up. Most often as a result of poor or cheap suspension/tire design relationship but sometimes a mechanical problem, ie; bad shocks, out of alinement, worn ball joints etc. It is usually exaggerated in heavier vehicles like trucks and SUVs.
 
Tire cupping can be as simple as a certain tires tread design not working well with a specific car / driver combination. Some tires cup, some don't. If the tires on your vehicle tend to cup, try something else, and make sure to rotate FREQUENTLY!

If the tires are already cupped, running tire pressures near the tire's max pressure can reduce / eliminate vibration and noise that often accompanies cupped tires. A harsher ride is usually evident, but gas mileage improves too...

Ps - tire guys will ALWAYS say its a balance / suspension / steering issue; they make money when you chase "problems".
 
Pretty common problem in that era of Ford trucks using the TTB (Twin Traction Beam) setup. The tire wear issue is one reason why Ford went away from this setup.

It could be as simple as all the bushings are worn out and need replacing (common in those systems) to bad shocks to bad tires or a combination of all three.

Take it to a good alignment shop that actually knows what they are doing with this setup. I'm betting on worn bushings/parts in the front suspension given the age.
 
Rear tires on a front wheel drive car will cup also if not rotated. Cupping is a problem on non-drive wheels and is worse when the tires have high tread on them. Once worn a little, cupping does not seem to be as bad. This is also a problem with heavy trucks (trailer tires) and some companies will put old steer tires on the trailers and keep newer tires on the steering axle, as the steering axle is the most important.
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Although I can't comment with authority on 4x4 front ends in this matter (isn't he Explorer independant?) ..the general cause of cupping is bad shocks or ball joints (traditional heavy front-end).

The cupping is formed by the tire "oscillating" undampened. The tire "strikes" the pavement and continues to pogo along. Eventually the entire tire is scalloped. Once the wear pattern is established..it never stops wearing like that and merely becomes more apparent with time. Although they've appeared to have conquered some tire wear issues (or at least contemporary dogma would indicate) at one time rotating was NOT recommended due to fact that one position on the vehicle would establish a given wear pattern that would continue to wear that way regardless of what new position the tire was placed. This would mean that eventualy, throughout a rotation evolution, that you would end up with 4 like worn tires ..while you would only have had to replace 1 or 2 if you hadn't rotated at all. This differs with a true solid axle 4x4 wear only toe is adjustable (for the most part). In these applications ..that's the only anomolous wear issue that you have any repair for.

That is, once slightly cupped ...it will most assuredly become severly cupped no matter what you do.

And for those referring to cupping on a 4x4 frontend ..are you sure you're not referring to "feather edging"? If so ..that is a toe issue.
 
I think the Exploder still had Twin-I-Beam in '95. It is vital to do regular tire rotations with this setup. The first rotation on a set of new tires at 5000 miles is the most critical. Read your owners manual.

I had a TIB Ranger and now have a TTB F-150. With proper rotations and replacing shocks when bad, I have never had tire problems. GM trucks on the other hand, seem to wear the outside edge on the fronts due to poor steering geometry.
 
Interestingly enough I have had tire cupping problems on my HD Road King motorcycle. These tires, as you probably know, cannot be rotated. The dealer told me it was "natural". This was with less than 22,000 miles on the front tire and it was not nearly worn out.
Motorcycle tires are soft rubber, but I noticed no unusual vibration when riding.
Go figure.
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quote:

but I noticed no unusual vibration when riding.

Usually the car owner doesn't either. That's why it isn't discovered until it's really apparent in the wear pattern. How much travel do you think a loose ball joint gives ....a few .100"?
 
Have you seen the reports on the new Nissan 350Z. They are having excessive front tire wear and road noise. The TSB says it is due to improper alignment-toe in from the factory. Tires are wearing out in less than 10k.
 
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