New Member, Info on Cupped Tires?

Hey guys, this is my first post here so bear with me;

I've been a long-time member of the Jeeping community, having owned many Jeeps over the years. I've become fairly knowledgeable with mechanics, I've always done my own repairs. However, I've never owned a vehicle with IFS before, and know basically nothing about it's design.

I recently purchased a 2007 Access Cab 4x4 with 191,000 miles on it, for the steal price of $5,000. It's in mechanically good shape NOW, but it's had some recent work done, including new brakes all around and new CV Shafts up front.

The truck came with a set of 245/75/16 Cooper Discoverer S/T's on it, Load Range E. The tires have less than 10K miles on them. However, the tires that were previously on the front got cupped pretty bad from the worn CV's, and are worn down to about half-tread. (That's some serious tread wear!) The tires that were originally on the rear look in brand new condition.

Now, the PO replaced the front CV shafts and rotated the tires front/rear so the good tires are up front and the cupped tires in the rear. The cupped tires are bad enough to shake the whole truck between speeds of 20-80 MPH. Also, the shaking is felt in the steering wheel when the brakes are applied, which would lead me to believe warped rotors, but the rotors are new?

So, what would you guys do? Take it in for an alignment and have them re-balance the tires? Run it and wait for the cupped tires to wear down, or replace the two cupped tires? Replace all four?

What're your thoughts? Thanks!

-Walt

 

Welcome ,

How would worn CV's result in cupped tires ? Isn't that more a result of incorrect pressures ?

Great deal on the price BTW .

 

Well, as far as tire pressure is concerned, it's generally a result of too little pressure and prolonged highway speeds.

However, I know on a solid front axle vehicle, it can occur from worn ball joins, a worn wheel bearing, tie rod ends.

I know very little about the dynamics of an IFS rig, the P/O just told me the cupping was the result of worn CV's. It wouldn't surprise me at all if it was something totally unrelated.

 

Bump for some other thoughts?

 

The cvs are not a structural part of the suspension. They would not cause cupping of tires.

 

hows the alignment on it? mine are cupped/cupping due to my alignment getting bumped out everytime I wheel it. You can save yourself a few bucks and do a quick check on the toe set at home. Get under the truck with a tape measure. Measure the distance from center of tire to center of tire front side and back. IIRC if the difference between the front and rear is 1/16" of an in toed IN thats good.

What condition are the steering components in? Tie rods inner/outer good shape with no play?

What kind of wheels are they, factory or aftermarket? (vibs)

 

I've also got a 2007 and for the life of me I can not figure out why my tires cup. It's not horrible and I can keep the tires even by rotating them regularly at 5,000 miles but since about 30k miles, the truck has cupped tires. A number of things can cause it, tire pressure, bad shocks, incorrect balancing, etc. I did some research and it seems cupping can be damn near impossible to diagnose.

Depending on how bad the shaking is, I'd run with the cupped tires on the rear if it's tolerable and try to figure out what's causing the front to shake so you don't cup those tires also.

 

Good to know! I'll look into the ball joints but they were fine with 0 play this past summer (checked them when I replaced my LCA bushings). Otherwise, we might be chasing the same problem. I've also got fairly new billies in good shape and can't figure out the cupping issue at all. My Coopers seem to show the cupping a lot more than my Bridgestones though...