tread cupping

On my DD I skimped a little and got the Firestone off-brand tires to save some dough. The brand is Primewell, and these are E-rated 245/75/16 with an HT tread. After 1500 miles they started getting a little noisy and I noticed tread cupping. Right away I took it in for an alignment (although my E350 van only has toe adjustment) and they said it was perfect... perfect enough that they didn't even charge me.

So I rotated them in the recommended way (cross the fronts to the opposite rear and bring the rears straight forward) and they still appear to be cupping. I know that once they start to cup its hard to stop, but is there something I can be doing to prevent this? Can I reverse it by swapping the direction?

(and don't say something smart like "don't buy primewell tires")

How are your shocks? Weak shocks could cause cupping.

Shocks. Alignment shop should have checked.

All right, I'll jump in with a related query: What causes sawtoothing?

Duke, aren't they the same thing?

... And about the shocks, all four are brand new KYB shocks installed about 7000 miles ago. That doesn't mean they aren't the cause, but its unlikely.

And the old tires weren't cupped.

Primewell tires SUCK. BTDT.

A Ford van, with twin I beam suspension and cheap rubber is cupping the tires.

It would be a much bigger news story if it were NOT cupping tires, I'm afraid.

Streetwiseguy wrote: A Ford van, with twin I beam suspension and cheap rubber is cupping the tires. It would be a much bigger news story if it were NOT cupping tires, I'm afraid.

Well, the old tires didn't cup. The tires on my F250 didn't cup. And the rear tires are cupping just like the front ones.

While I'm not a huge fan of the twin I-beam geometry, its hard to beat the strength of 6 feet of forged steel and a large kingpin holding the caster and camber in place. Never had an ounce of trouble with either of mine.

I think its obvious that the tires are to blame, I'm more concerned about how to prevent further cupping and possibly reduce the cupping I have (without resorting to 10 minute smoky burnouts every 3000 miles... but I usually do that anyway.)

Just chewin on you. If the old tires were fine, its the new tires fault.

Streetwiseguy wrote: Just chewin on you.

Hey... buy me dinner first.

If the previous tires didn't cup, and these are cupping, I'd also say the problem is in the parts changed & work done. Most likely, imo, poor balancing of the tire/wheel assembly. Poorly formed tire (non-uniform, twisted, etc) would be a second most likely cause, again, imo.

Once a tire is cupped, it is incapable of rolling smoothly along the road. So it can only make itself worse.

I have heard of shaving a cupped tire to get it round again. No experience with this whatsoever. Considering the quality of work I've seen by most shops with tire shavers, I have my doubts about their ability to actually make a cupped tire round.

Shocks were my suggestion too. I just put shocks on our 4Runner last night for the same reason. So, I dunno. But if they're okay, I'd guess it has to be some kind of alignment issue.

Duke wrote: All right, I'll jump in with a related query: What causes sawtoothing?

Too many burnouts?

Really though, here's some good information:

http://www.procarcare.com/includes/content/resourcecenter/encyclopedia/ch25/25readtirewear.html

Feathering (which is what I imagine you mean by sawtoothing) and cupping are different things.

"Cups or scalloped dips appearing around the edge of the tread on one side or the other, almost always indicate worn (sometimes bent) suspension parts. Adjustment of wheel alignment alone will seldom cure the problem. Any worn component that connects the wheel to the car (ball joint, wheel bearing, shock absorber, springs, bushings, etc.) can cause this condition."

foxtrapper wrote: I have heard of shaving a cupped tire to get it round again. No experience with this whatsoever. Considering the quality of work I've seen by most shops with tire shavers, I have my doubts about their ability to actually make a cupped tire round.

I suck at rotating tires, and the shop that saw my truck last week said that the fronts were cupped pretty bad, so they put them on the back. He recommended I go do a bigass burnout to make them round again.

The only way I know to get rid of cupping is to shave the tire down flat again. Reversing rotation has never worked for me.

In this case the cause is either bad tires or play in the kingpin. No ball joint problems, etc. since the truck doesn't have any of those.

Could be a bad balance......my 92 sho did that fairly bad due to a wheel weight falling off.

My '03 GMC 1 ton van has the same problem (cupping). Both upper ball joints were trashed as well as both hubs. Replaced all that, tires are still cupped but getting better as they wear (vibrates less). Getting shocks next.....trying to convince SWMBO that we need Bilsteins instead of the Monroes that are cheaper. We live on dirt roads BTW. Rode in my friends truck with Bilsteins, what a difference!

place I worked at had E350s.. they ALL cupped their tyres.. usually the rear for some strange reason. After a while, they would get very noisy and vibrate like crazy from 60 to 70mph... which made highway work fun

Every single Ford van/ truck that I have ever worked out of (6 throughout the years) has eaten tires. Cupping is a given with a Ford if you ask me.

curtis73 wrote: Duke, aren't they the same thing?

No, cupping looks like you scalloped the entire circumference with a drum sander. It's usually caused by uncontrolled oscillations in the suspension, from worn or damaged parts.

Sawtoothing means the leading edge of each individual tread block wears more than the trailing edge (or vice versa), so the tire stays round, but the tread gets noisy. It makes the tire look like a sawblade when seen from the side.

Alan, I looked at that link, but feathering's not what I had in mind. Feathering is parallel with the plane of rotation. Sawtoothing is perpendicular. I've had it happen on sevral different cars over the years. My Conti DWs are doing it on the 3er.