tire cupping

[dakota goat]

Anyone have a problem with front tire cupping?
Mine started at 7500 miles after a tire rotation and balance.
Dealer said drive it 1000 miles and let's see what happens. I'm nervous.

[miamio]

don't let him prorate your tires at 8500 miles if they have to replace them, make them do it at 7500 when you first reported the problem.

[Huntress]

Dealer said drive it 1000 miles and let's see what happens.
Get it in writing. I suspect he will be replacing your tires since it is probably an out of balance condition.

[2Cool]

Define cupping... as in scalloping along the inside or outside edge? Excessive wear of the mid-tire tread? With an exact description, we can diagnose the causes. Scalloping can be attributed to bad toe settings or bad shocks, outer edge wear can be toe or camber, wear on both outside edges with mid-strip fine is underinflation, mid-strip wear is overinflation. Lots of potential issues, describe the exact sympoms.

[CMNTMXR57]

Generally cupping is from under-inflation which is the users responsibility, not GM or the tire manufacturer's.

[anmracing]

CMNTMXR57 is right. Cupping is never covered under any manufacturers warranty. You would be very lucky if anyone did a pro-rata adjustment on a tire that is cupping. There are many variables that could cause cupping. It is recommended to rotate tires at 5-6,000 miles.

[dakota goat]

CMNTMXR57 is right. Cupping is never covered under any manufacturers warranty. You would be very lucky if anyone did a pro-rata adjustment on a tire that is cupping. There are many variables that could cause cupping.It is recommended to rotate tires at 5-6,000 miles.

The cupping started at about 7500. This was the second rotation and balance. The cupping is all on the inside tread rib of the tire . The other front has started also. Tire pressures have always been 35 lbs.

[CSiJason]

Inside? Are you drifting the thing around corners real hard or something? The only other thing that would make only the inside wear out quickly is bad camber which shouldnt be a problem unless your car is lowered. (Even then, you'd have to lower it more than an inch to make the camber bad enough for it to wear the inside out quickly.)

I'd take what the dealership gave me in this instance. Tires are not typicaly something they cover under any conditions since they are a major wear component.

[Bob by Chicago]

Radial tire cupping is caused by uneven scrubbing or scuffing, that once started gets progressively worse. If allowed to continue the cupping of the edge would grow diagonally further across the tire. Usually the noise created gets the tires replaced because of a rumble situation that can eventually turn into a resonance and be incredibly annoying to the driver. Chances are good that the inside cupping was started in the rear and became more noticeable when they were moved to the fronts. Pretty common on vehicles with IRS. Even worse on FWD vehicles (but that is another story).

Camber wear alone will generally cause edge wear if severe and to some extent it would be normal to have a little quicker inner edge wear due to the negative camber in the rear of our vehicles. But camber wear is pretty consistent, or even all the way around the tires.

Our rear camber spec is -1.05° which is a bit for a daily driver but not too crazy. The catch is, the tolerance is .63 which means that any thing from -.4° to -1.7° would be ok as far as warranty goes. Again camber alone will not cause cupping, but if off by much will make the tire more susceptible to toe error.

I would expect to see toe error as the root of the cupping. All the angles are interrelated. Our rear toe spec is fairly severely toed in when it is right-especially in the rear. Our toe spec is +.4 (Toed in) with a tolerance of ±.34°. The truth is that doesn’t really mean the car is "Right" at anywhere from .16° to .74°. It just means the dealer won’t have to align it under warranty if it is. In the rear, when you step on the gas the torque will tend to make them toe in even worse and then toe out a little on de-cell. Not much but if they are "not right" to begin with it will only make it worse.

The problem could also be happening on the front axle, but the nominal alignment specs and tolerances are much narrower and less radical up there.
The KDWS that came on these aren't particularly soft or sticky, so what ever is causing the problem on them would be worse on something with more grip.

Whether it is covered by under warranty or not, I suggest you get an alignment check. If for no other reason, to ensure that whatever you put on to replace them, won’t have the same thing happen to them.

[CMNTMXR57]

Bob beat me to the alignment issue.

If it IS in fact an alignment related issue, that is a factory setting, then the tires will be covered. IF the alignment is off due to lowering or some other form of suspension modification, then I doubt they'll foot the bill.

Bob, where did you get these specs. I'd be interested in knowing as I think my fronts are wearing a slight bit unevenly.

[Bob by Chicago]

Bob beat me to the alignment issue.

If it IS in fact an alignment related issue, that is a factory setting, then the tires will be covered. IF the alignment is off due to lowering or some other form of suspension modification, then I doubt they'll foot the bill.

Bob, where did you get these specs. I'd be interested in knowing as I think my fronts are wearing a slight bit unevenly.

I cant post them as I got them from Mitchell1. I don't have GM or Mitchell1 permission. I will try to find a version I can either post or just give them. I will check with a connection at Hunter Engineering and see I can work something else out. Give me a little time.

[CMNTMXR57]

10-4. Thanks.

[Jeremy@FredBeans]

I can tell you right now...don't assume your alignment is good. I work at a dealership. My GTO was drifting slightly to the right and my steering wheel was of to the left. The alignment on my car was the worst they had seen on a new car in quite a while. GM's policy is to drive it 500 miles before they will align it under warranty. Not sure what happens when it has 7500 miles. But the alignment should definetly be checked by the same dealer.

[GTOTECH101]

Yeap, common problem on all of these gto's, most likely left front? I think that from all the shipping these cars went threw that the alignments are way off. My other
thought is that the alignment spec's are set for a right hand drive car and meant to
be driven the the left side of the road. Hear in the state's you have to compensate
for the crown of the road. If they drive opposite of us with the same alignment spec's
this could also cause the tire's to cup on the outter edge, especially the left front.

[GTO-HANK]

During an oil change at first 1,500 miles, the Tech noticed some "feathering" on the outside edges of the front tires. He suggested an immediate alignment check. After I found my car was delivered with tires at 65 lbs all around, I had no confidence that the alignment would be correct either. So I took it to the dealer the next day.
The alignment was way off.....too much toe in (triple amount recommended) and too much camber. (don't remember the actual #'s).
All work was under warranty.
P.S. Gave Tech a good tip.
P.S.S. Had a small rock hit windshield directly in my vision path. Had a real problem finding any "glass dealer" that had the correct molding. Seems as though none of the "normal" USA stuff (too narrow) will work, a specific required dealer supplied item. If you are friends with your local dealer, you might suggest they inventory the molding!! (Not a high dollar item)