Learn Me Cupped Tires

Good day!

I noticed that the tires on my new to me 2011 Silverado are cupping a bit.

What the hell causes this?

How do I fix it?

The truck drives nice, doesn't pull one way or the other. The tires are the originals (I think) 30,000 miles.

Is it a toe problem? Can it be over-inflation?

Any help is appreciated!

Thanks!

Rob R.

I think SVreX had a similar issue with his truck a while back. I don't recall what the solution was.

That was even more than less than unhelpful.

My Z71 tires cup. I rotate them every 10k miles and have no issues now. The front tires always round a bit then when I put them on the rear they square up almost immediately.

I have had it aligned twice and regular rotation has been the onl real fix. They have lasted as well as any other tires also.

I think it has to do with the large (or ~larger~) tread blocks, insufficient caster angle, and insufficient Ackerman. Not that there's much you can do about it.

I've never had it before but I have read those tire diagnostic charts on top of the parts counters and I'd swear it had to do with your shocks.

I have heard it can be shocks. The shocks on the truck pass the driving down a bumpy road test as well as the push down and watch rebound test.

I am not sure how else to check the shocks.

In reply to FranktheTank:

This.......just rotate them fairly often. Our fords do the same thing.

I worked for a major trucking company for 6 years and bought literally millions of dollars worth of tires. I never once in that time heard a tire rep give me a definitive answer on why it happened, because they did not know.

Regular rotation should keep control of cupping.

Bad shocks can cause it too, but usually it's just a rotation issue.

Check your ball joints?

it used to be accepted knowledge that cupping was from worn shocks ... but that was MANY yrs ago ... could be more to it than filling station mechanics knew back in the day

Yeah, if i had a serious tire cupping problem, i would try shocks first, and then more frequent rotations. And if that didnt fix it i would change tires, and if that didnt fix it i would give up and deal with it / sell it. This all assumes you've checked the alignment.

If I had to make a bet it would be on toe angle as the primary culprit. However, some tread designs are more prone to cupping than others.

Years ago in a previous life I managed a tire store.

There can be several issues. One of the most common is toe, and usually it is caused by the tire being slightly "drug" down the road, so to speak. It can also happen, especially in trucks, when the back has a load and takes weight off the front. Poor shocks are also a cause. Rotating them will help, but rotating and fixing the problem is the correct way to go.

On some cars such as my old G35, there is an actual design problem to deal with. In it's case, it was experiencing weird toe changes. Later model control arms and stiffer bushings in that case was the cure.

At least in the past, GM's were known to go through things like drag links and tie rods, so you may want to check those and make sure all your front end pieces do not have play. We used to take bets on any GM truck that pulled up as to whether they needed them, or Taurus's needing inner tie rods. You got where you tell what a car was going to need before you put it on the lift!

It's not toe or castor or camber. At least often not because it happens in all wheel positions. I have seen brand new tires on brand new trucks ruined by cupping in a few months.

My theory about shocks causing cupping is that a shock may handle the large/obvious motions well, but if it doesnt damp the first ~1/8" of travel away from 'ride height' it can allow tiny oscillations that can cause cupping. I dont know if it's true, but it's the only way i can attribute cupping to shocks that otherwise 'feel' normal.

Worn out shocks that let the tire 'bounce' down the road can cause it, as can mis-alignment. Excessive negative camber combined with excessive toe-in will cup the heck out of the tire.

Rotating the tires doesn't do anything but -- wait for it -- cup the tires that came from a location that didn't have the problem. Unfortunately, once they're cupped, it's pretty difficult to 'uncup' them. You can, and should, correct the problem that caused it. But fixing the noisy tires that result is pretty tough.

I've chased this on my Cooper - significantly out of alignment when brand new. Because it was new, I didn't think it could be that misaligned - and cupped my second set of tires (rotated them and cupped the two from the other end of the car too!) before I finally woke up and put the car on the rack. Almost 3 degrees negative camber at the back on a spec of -1.7 degrees, and about 3/8" total toe-in on a spec of about 1/8" total. It was 'dragging' the rear tires down the road. I've gotten them to run a bit quieter by, believe it or not, doing repeated 'skidpad testing' in empty parking lots running both ways to literally wear down the cupped part of the tread. A bit quieter each time I do it.

Highway fuel mileage picked up about 1.5 mpg after the alignment.... LOL

The answer is frequent tire rotation. Or Miata. I can't remember.

yes, ball joints, possibly. Wheel bearings also? Shocks possibly?

The_Jed wrote: I think SVreX had a similar issue with his truck a while back. I don't recall what the solution was. That was even more than less than unhelpful.

You've got a heluva memory!

"Cupping" is not a descriptive enough word to answer the question. There are different types of wear, and different types of cupping that indicate different things:

My problem was slightly different. The tread blocks were wearing unevenly in the direction of the rotation (wear across the face of the tire was even). We eventually called it "normal" for a larger truck, and I started rotating more frequently.

It's kinda hard for me to expect a perfect ride without issues from a 450,000 mile truck!

Is this something that only happens to trucks? I've never owned one, and none of my cars have ever had this problem either...

According to that chart, I have cupped edges.

I have a 2007 Silverado, the new body style, not the classic, and had the same tire problem. Rotated every 6-7k miles and that was the best solution, unit the upper ball joints wore out at 75k miles. Then I got all goofy and instead of just fixing them, I 'upgraded' to stupid big beefy aftermarket upper arms. The one single thing they changed was caster. I went from the stock 1-1.5 degrees of caster to almost 6 degrees. Aside from the steering benefits, the goofy tire wear went away completely. 20k miles and no rotations and everything is perfect and even.
This isn't really a solution to the problem, just a single data point, make of it what you will.
Edit: I also replaced the shocks with quite different ones from stock, so if Vigo is right in his theory that might explain it as well, but the truck had E36 M3ty tire wear from brand new even with a good alignment.

Cupping generally is caused by the tread configuration. Large tread blocks wear unevenly. Reversing direction of the tire by rotation will help to eliminate the problem.

I remember from my time working a few tire/service stores that some of the tires sold had more of cupping issue than others. Usually the more expensive the tire, the more chance of cupping, as the tread blocks get bigger and the purchaser more picky. The $50 or under tires have pretty narrow tread blocks and the folks buying usually don't pay a lot of attention anyway.