Newish tires gone out of round?!

I put a set of Michelin Pilot Sport AS/3+ tires on the GS430 a few months back and they only have a couple thousand miles on them. I was noticing some "hopping" to the front end at low speeds that translated to a heavy vibration at high speeds, and was dreading having to replace the wheel bearings as they're non sealed pressed on things that are tough to replace (for me, at least). Well, when I jacked it up to put the winter tires on I checked things out and the bearings seemed good. But spinning the tires and using a reference point made it clear there was something wrong as at a particular point in the spin the tire was farther from the reference point than in the rest of the rotation. I hope that's clear enough. Anyway, I put the winter tires on and the problem went away. Yikes!

I don't see a visible flat spot in the tires, and the car has ABS. Is it possible the tires have gone out of round? What else can I check? The tires are under warranty and have road hazard protection, but I'd like to gather input before taking them back to the tire shop.

If the car's been parked for a while, especially on hot pavement, the tires can develop a persistent flat spot just from the weight of the car sitting on one spot for so long. The only fix is to get the tires hot a few times and they'll work themselves out.

If it's not a structural flat spot from sitting, the only other possibilities are a defect in the tire, or that the tire slipped on the wheel and needs rebalancing, which is very unlikely.

Will a Road Force Ballancing reveal this defect?

Sounds like a belt in the tire has shifted. Take them back. Visual inspection or placing them on a regular balancer will show the defect.

In reply to GameboyRMH:

Tires have not sat; car is daily driven and the tires are only a few months old. I'll take them in. Sucks too - they were expensive. Now I'm afraid of the new ones doing it if they replace them!

Two thoughts.

First, are you sure that you don't have a bent rim or rims? Some cars have shockingly soft factory alloys. (BMW and SAAB come to mind)

Second, I've experienced way more disappointment from top shelf tires than mid-grades and cheapies. I would never buy a set of Michelin Tires if I had other good options. Goodyear and Metzler have let me down too.

Yep,

Sounds like a broken or displaced belt. Take them back and get them replaced.

In reply to HappyAndy:

I am running aftermarket wheels on these tires, and I did not inspect for bent wheels. I will look. They were perfect when the tires went on, and I haven't hit anything that I recall, but my wife drives the car as well. They're Koenig forged wheels so not top shelf but also not super cheap.

Disappointment goes up directly with the cost. If these have had broken/damaged belts I'll be pretty disappointed.

It's amazing how potholes destroy tires. They happen faster the shorter the sidewall.

Yes, take them back and get them checked out. I sell lots of these and hear good feedback about them, but nothing is perfect.

Good candidate for a Road Force balance. It will answer your question and also be documentation to use towards warranty replacement.

Its strange that two tires on the front have the same factory defect but not the back tires. I vote for something was hit, (railroad track?) and damaged the belts.
I would go to the tire store and let them put the wheels on the spin balance machine to observe the condition. If its there, and the tread depth is the same at the high spot, I would go for dismounting and an internal inspection. I suspect you will be buying new tires after the results of that inspection are known.

jharry3 wrote: Its strange that two tires on the front have the same factory defect but not the back tires. I vote for something was hit, (railroad track?) and damaged the belts. I would go to the tire store and let them put the wheels on the spin balance machine to observe the condition. If its there, and the tread depth is the same at the high spot, I would go for dismounting and an internal inspection. I suspect you will be buying new tires after the results of that inspection are known.

This. Not going to be warranty unfortunately. Likely pothole/railroad track/something.

EDIT: shouldn't be warranty is what I should say. Some shops will "Warranty" for customer service, but it's just them eating the cost of hte tires. The manufacturer will tell them to take a flying leap, not a defect. To them, defects are something that is found at the time of install, not months later with a lot of miles on them. Michelin was one of hte hardest for us to deal with at the dealership in terms of manufacturers warranty.