Cupping of tires? tie rods or just bad tires?

[Garfield2]

I have a new "used" 1996 Park Avenue. It has BF Goodrich tires on it and I noticed that when I drove around 70mph it had a slight shake in the steering wheel. I took it to Wal-Mart and they re-balanced the 2 front tires. 7.50 lifetime balance. Now it seems to shake at around 50 mph, but not too bad at 70. Weird huh?

Took it to another Wal-Mart and he felt the tire and said there is cupping on the tire and wouldn't check the balance. Thought there was some problems with either the shocks or tie rods or ball joints. Shocks appear fine. You push up and down and when you let go they immediately stop and right themselves. I changed oil and felt the front tires. You can move them ever so slightly if you push-pull side to side on the tire when it's up off the ground.

Is the cupping a problem with connecting rods or is it just something with those BF Goodrich tires?

[Blue Bowtie]

I doubt that it is the fault of the tires. You need to resolve the problems with the loose steering linkage before you can expect the problems to disappear. What you can do is to rotate the tires and rebalance.

[Garfield2]

Took the PA to the shop today and they flushed out the brake fluid and replace. I also had them check the shocks, tie rods, and lower ball joints. All were in good shape. Shocks and front suspension is not causing this, but they thought perhaps that the rear tires might be out of alight slightly and that the cupping came from the rear tires as they were rotated to the front. Any thought on that idea?

Or....could be that the tires were badly balanced to begin with and wore this way because of the balance. I see that tire balance can cause cupping of the tires as well.

[Salestax]

Can be caused by worn suspension components, improper inflation, shocks, struts, lack of normal rotation (every 6000 miles)

If you want to invest in new rubber, start there. If you felt 'play' in the front end and the shop didnt, have 4 wheel alignment done (not a 2 wheel thrust), rotate on a regular basis and see if you get 70k out of your tires.

[Garfield2]

Come to find out that with 24,000 miles on the tires (thereabouts) he had rotated them once quite some time back. Seems that lack of tire rotation on these tires causes them to wear poorly, on the back. The light weight of the back end with an empty trunk lets the tires develop a very slight 'bump' going down the road. If there was lack of good balance then that would also have contributed to the conditon.

More like a "Heel-toe" wear pattern, ie: higher rubber on the tread on the leading side of the lug and less of the tread on the back trailing side of the tire lug.

I've also seen a forum note on certain tires to be more "quirky" to this than others. Seems the ones with the sipes that run more vertical to the tire rather than horizontal across the tread develop more of a "chance" for this to happen.
Vern

[Bassasasin]

You might have a damaged belt in a tire.. otherwise the tire is skipping or slipping through part of its rotation cycle. Allignment might help, a good shop will find a problem. A bad shop will invent one.
Other possible causes
loose wheel bearings
mismounted tire/ wheel assembly
out of balance wheel assembly
tread design/ tire design
worn bearings, shocks, springs or other suspension compnents

Good luck

[Garfield2]

Originally Posted by bassasasom

Allignment might help, a good shop will find a problem. A bad shop will invent one.


Good luck

Ahh therein lies the absolute truth. FINDING a good, honest, alignment shop that does not invent stuff.

Took my old 1993 Park Avenue to a local guy at Fennville. Had a funny noise in the front. He drove it around the block and told me that I would have to have him replace the CV joints as they were bad. Took it out to some other folks I know that do a great job on mechanic work ... Father and Son near Fennville, and had some other work done and asked them to tell me what they thought that "poping" noise was about? Got the car back and they did what they were asked to do and a VERY reasonable rate.. and the popping noise, that the tire shop said I had to have the 2 front CV joints replaced.. well it was a cap washer that fit on the bottom of the car at the suspension bolts. They replaced the ones that were rusted away. No charge. No popping anymore either.

[TommySS]

If you have tire cupping problems, the suspension (shocks/springs) is not strong enough to keep the tires planted on the road. I just went through this on my mom's 99 PA. The overall suspension squishiness I was feeling was not normal, even for a PA. The front struts had no gas-charge (leaked out from sitting so long).

Far as I'm concerned, once they're cupped, the tires are shot. But if you replace the tires without fixing the problems, they'll cup out on you in very short order.

It also helps to rotate/balance/align regularly. I rotate/balance every 6k and align every 12k. Shocks as needed, but if I get to 100k on 'em the springs get changed also.