I have a 99 psd 4x4 ext cab short bed. the tire i have are 285 75 r 16's cooper atr's and the issue is tire cupping. its like the tread is pitching from the front to the rear. i am thinking it's shocks but i am not to sure. any ideas? the tire wear will show in less than 1,500 miles and when i am slowing to a stop i can feel the chop in the tires. the tires are new and have about 10k on em. I rotate every 5k but the cupping is faster than the rotation ca fix. help!!

 

Take your truck to an alignment shop, and have them align it, I think the reason they cup like that is because its towed in or out too much. Mine do it slightly, but a rotation takes care of it, and Im happy with how it handles, but it sounds like yours is excessive, and needs to be adjusted. Before you spring for shocks, see about getting it aligned IMO

 

Sorry but I disagree. Too much toe in or toe out causes the outer or inner tread to wear. Cupping is generally due to worn shocks or overall looseness in the steering components resulting in the tire hopping up and down while under way.

 

Do you see the problem on all 4 tires? Both axles?

 

Agreed, cupping is usually shocks, but what you are describing might also be feathering or a saw tooth wear pattern, which is also caused by misalignment or loose steering/suspension components.

This web site explains it:

http://www.familycar.com/CarCare/AlignmentBalance.htm

Take your truck into an alignment shop, have them check it (they usually do this for free). They will give you a list of what is worn out and an estimate to repair it. It's your option to pay the price or do it yourself.

 

I had new bilsteins put on about a month before i got this set of tires, which are now almost wore out, steering is tight, my tires have slight cupping on the outer and inner tread blocks. The center tread is perfectly fine. Im not sure if he has the same trouble or not, he just said it was pitched from front to rear, but not weather it was the whole tread, or inner or outer. I would still get it aligned as the first step. I have a hard time believing shocks could fix this anyways, because we have quite a few sd trucks, with over 160k with factory shocks, that do not have any issues with tire wear. I could see that being more of an issue on an lighter car. No offense.

 

Outer edge wear with the center unworn means you're running the tires underinflated.

Most owners will tell you that the factory shocks are junk after 30,000 miles. I'm shocked you still run them at 160,000 miles.

 

Its definitely a good idea to get a free assessment and estimate from a front-end shop. But you don't want to pay for an alignment until the worn parts are replaced, whether they are shocks, stabilizer bushings or whatever.

Besides, Guthrie, where are you ? What's the mileage on the shocks and front end? Does this bad dude have 20,000 miles, or 220,000 ?

 

I find that cupping on these rigs is often an indication of bad ball joints.

 

What i meant by outer edge, is the outer edge has a slight saw tooth look, like he said, and the center tread has normal wear. My tires actually have more wear in the center due to too much pressure, but its pretty close and the center section is straight like it should be. I like running my tires at 65psi all around, and like i said before, its within 300 pounds of equal front to rear weight distribution with all my junk in the back, i checked it on a scale. I dont still run factory shocks, some of the other trucks at work still have them, but the people who drive them dont seem to care.

 

If it isn't severe, rotation will usually take care of these problems.

 

I have been studing tire cupping in public information for about 2 years. Our Mercedes has this problem . Everyone wants to throw $$ at the vehicle to solve this problem. Shocks,, alignment,, parts etc. This might be the issue, however this problem is very large in magnitude. I have actually called the mfg of tires to discuss this problem with them. Their answer,, you don't have enough tire pressure or it's your car's fault not our tires.

The mercedes has coopers and they have cupped with noise now louder than the radio. (note same brand on the Ford truck that cups)

I have found that TIRES in most cases are the reason for cupping but the tire mfg won't accept this and there is no definitive proof. Our Mercedes has been checked by Mercedes reps and a independant and verified there are no issues with our vehicle. However cupping still continues. Even road force balance doesn't solve cupping. I have easily spent over $400 on just inspections not to include a set of tires at $400 each to still have cupping. I have found this problem on Ford Tarus, Mini Cooper, F250's, Lexus,, Mercedes. So it is not exclusive one make or type. However I have found a semi common thread. Tires made in Japan and larger than 15" and a agressive tread design seem to have this problem more pronounced. (there is no scientific proof to this only my observations)

Tires made in Germany haven't been found to have this problem, at least not yet. The difference in the tires are the way the belts are made and joined, tread pattern and rubber compound. (much of this is confidential competative info in the tire companies). I only have the data they provide to the public.

But I always ask why not German tires but other brands.

Yesterday I had enough. I filed a complaint with the NTSB on tires. With shocks at $1400 each and tires over $400 and alignments at $200 each balance at $25. and nothing work it has to be the tires.

Tires found to cup from public searches. (do a google search and you will find the same information)

Goodyear
Toyo
Cooper
Bridgstone
some Michelin

This doesn't mean all the tires but it does appear based on my analysis of information provided in public sites. So my assessment might not be correct. But you must ask yourself if you have cupping. Is it aligned, maintained, balanced, tire pressure at least at recommended. If you have done these most want to buy shocks. So do your tires bounce while driving, if not probably not shocks. That only leaves tires. So quit throwing away, I have seen some new cars with replacement tires cup out.

EDITTED by moderator krewat - no legal discussions



Jim

 

notice it more on the front than i do the rear. I do run helwig overloads on the rear so my suspension is very tight in the back. But the front is were i do see most of the wear but....... when i do rotate the tires, the tires on the back are running opposite direction than what they did wear so it will try and smooth them out.

 

I am located in north carolina and my truck has 198k on the clock. the shocks have....around 70- 80k maybe. i am a bit unsure what the mileage was when i took my lift kit off. It has monroe reflex shock on her. do you have any recomendation on what shock i should be running?