what is doing this to the tire? (98 forester)

[AKIRA]

Hello, my Step-mothers car is a 98 forester and it has a problem with tires on the right-rear wheel.

 

three times now a new tire put on the right rear side has become this within a few months:

 

http://img120.imageshack.us/img120/9995/tirevx4.jpg

Thanks to ImageShack for Free Image Hosting

 

it vibrates in the back when driving, obviously. (when I borrowed it I assumed a wheel was out of balance)

now Walmart (where she bought the tires) have said the treads are separating and replaced them each time.

 

any ideas on what is causing this?

 

thank you.

[porcupine73]

Hi. Common causes would be alignment issue, strut worn out, suspension component(s) worn. Obviously you know it is not a good idea to put just one new tire on unless all the tires still measure within 1/4" circumference of each other after replacement.

[wtdash]

Going w/bad strut..based on the tire wear. Over a 100K on the Forester? Probably due. And yes, one could go south while the other is fine.

 

Also, Foresters are know for rear wheel bearings going out, too.

 

Good luck.

[Setright]

Hmmm....a worn damper(shock) would cause cupping of the tyre surface, but I wouldn't put my money on it causing carcass separation.

 

Maybe the tyres are really lousy. Or they are being massively over-inflated causing undo stress on the carcass.

Or they could be under-inflated, and driven fast enough to overheat and cause the separation.

Have Walmart replace the tyre again, then take the wheel to another shop and have them balance it. Make sure you run the correct tyre pressure (28-30psi?) and see how you get on.

[Rooster2]

Agree with what others have written. Something is wrong with that corner of the car. Put the car up on a lift, using the type of lift that lifts the car's under carriage. Visually observe the wheel alignment to see if the tire/wheel looks like it is aligned vertically straight up and down, and not tilting to one side or the other. Also, grab the road wheel to see if there is any loose suspension movement, when pulling it in and out. Look to see if there is any oil coating the outside of the strut. That would indicate a leaking strut. Also, when the car is on the ground, push up and down on that corner of the car to see if the strut provides good shock resistance, or is simply acting like a cheap bug sprayer unit.

 

Try all of the above, but not at Walmart. Walmart hires the dumbest guys to work their auto shop, so don't expect them to be any help in solving your problem.

[aircraft engineer]

and check the wheel for run-out. Usually that type of wear pattern is a bent wheel or other bent suspension part (Like that one side is out of alignment)

 

If you can, get it up on the hoist and then run it a bit and see what the wheel looks like - I bet it wobbles

[idosubaru]

that's really bad. i would almost wonder if that tire is dragging or lagging. like torque bind, ebrake or rear caliper, wheel bearing, axle, rear diff? i'd want to jack it up and make sure it spins freely.

[uniberp]

That appears to be an alignment issue, possibly combined with bad control arm bushings.

 

The static alignment may be okay, but when brakes or gas are applied, the bushing compresses and pushes the alignment out of whack. Once a wear pattern like that gets started, it is self-amplifying.

 

Foresters are not easy on tires to begin with, small car, big engine, high center of gravity.

 

A good local tire store, or maybe a Firestone, might be able to help you out.

[nipper]

Thats a bad strut. Thats the worst case of cupping I have ever seen. Drive down the raod at 30 mph and up to your normla highwya speed. Have a freind follow you. Lets see if that tire is bouncing.

 

That vibration your feeling is both the cupping of the tire, and the tire bouncing on and off the road.

 

 

nipper