Wavy rear tires... second set.

As an auto technician (a previous carreer) I can tell you that:
A) the problem you describe IS caused by misalignment (camber/toe problem) and/or bad shock absorbers, and
B) just because the alignment is "within specs" it doesn't necessarily mean that it is optimal.
A good alignment tech who has aligned many Prii will know what the best alignment parameters are.
I would see if I couldn't speak to him and pick his brain about it.
Yes, the engineers set the specs on paper to be optimal however, experience has shown me that what is on paper is not always the best in the field.
If sticking or loose wheel hubs were your problem, you'd feel that a long time before tire wear were a problem.
Same thing with brake issues being the cause.
It's much more likely that a bushing somewhere in the suspension has "flattened" or is soft causing misalignment.
Sometimes it is a real pain in the butt to get an alignment corrected so as to not wear tires as in your situation.
Good luck.

 

We went through this years ago with a Taurus wagon. Had a bent axle by the hub. If your put the car in the air and ran the rear wheels you could see the wobble. With new tires it was quiet for awhile then the noise came back as the tread wore down. The car ran straight so alignment didn't effect the issue either way. You may have a bad wheel or axle.

 

thanks for the update, this is a sad saga.

 

I had exactly the same problem only at 190K miles. Ruined two pairs of tires. Replacing the rear shocks cured the problem. There was not that much difference between the new shocks and old. I would replace the rear shocks just in case, they aren't that expensive compared to ruining tires. There could be some kind of resonance setting up causing the up and down hoping, and changing the shocks will change that dynamic.

 

Did you buy the car new? Any chance it was wrecked and not repaired correctly. If you drive through water onto dry pavement and the tracks don't line up the unibody/subframe may be off.

 

I read your first post and then glanced over at where your from and said shocks.

Never even heard of brake issues causing this problem. And most used brakes with shoes don't contact the hub real good as you turn the wheel. There may be a free spot and then it catches a little which is meaningless when the weight of the car is on the wheel. If that effect is real bad one of the shoes is not free. But your from Maine and I bet there's substantial rust in the brakes. The star adjuster is probably a block of rust and all the springs and shoe mount tabs and base is solid rust.
Snap a picture of the back of the wheel area so we can see how bad its corroded.
But anyway replace the rear shocks. They were really only good for about 75,000 tops on good surface. Cut that in half in Maine. And the front struts are toast to. The car must handle very poorly.

 

Dude, not all tires are made the same. The stock tires are always better than the retail one. Take care of the stock tires and it will save you money on performance as well as time.
Keep checking tire pressure, keep it clean, etc. should exceed warranty expectation.

 

But it galvanized steel! unless your car is so old and the coating have scratch off, or you spray extreme harsh chemical on it daily!

I just found out that cleaning your car belly is unnecessary and only wash away the protect ant chemical. The more you clean it the more vulnerable it is to chemical harms.
I found filtered drinking water is better than tap water and rag is better than hose.

 

and a day at the beach is better than a sharp stick in the eye!

 

It sounds like the belts are delaminating in a circular pattern. This can be caused by improper thrust alignment. Have you had that done by a specialty shop? (align both front and rear tires and make sure they are also on the same track, not off-set, or "dog tracking" as we used to say in the sevendees) I had that happen on a solid rear axle front drive car years ago, and the thrust alignment cured it.

 

I was referring more to the roads in Maine being harsh on shocks.
But as a side note corrosion must be really bad under there too.
I love Maine. My wife's from there & lots of family near Portland.

Try this. Have someone drive down the road in the Prius on a highway and you follow along behind and watch the rear wheels how they handle small bumps. I bet the rear tires are jittering around pretty good. I see this all the time on cars. Smooth road and the tire is doing a micro dance on the road= very bad shocks.

 

Dude, stock tires usually suck and especially suck on a Prius. Goodyear Integrities are the worst tire ever made, maybe as bad as Goodyear Wrangler
RT/S. Which is a stock tire on millions of Ford trucks & SUV's.
Both tires deserve a class action lawsuit imho.

 

Hmm..not sure what that means as there is no heavier part of the tire. Some tires are directional though but it sounds like they were all balanced good as no vibration. So not a tire problem. I'm running Kumho Ecstea's too. Love them.

But try what I suggested and look closely at the rear tire and see if they are planted real good on the road with no jitter.