Is it my struts or tires?

I drive a 2002 Solara, 4 cyl., with 60K on the ticker. The rear end has started to hop around when I hit a bumpy road; it’s just not sticking. I bounced the corners of the car to check the struts, and those seem fine (i.e., it doesn’t continue to wobble when I take my hand away, it just returns to position). My mechanic attributed the problem to tires that are wearing unevenly. The tires are 2 yrs old with 20K miles - I check the inflation at least semi-regularly - but, I thought bad suspension causes tire wear -

Is the hopping my struts? Tires? Another shop told me a few months ago that one tire was cupping, but had nothing bad to say about the others -

Cupping usually means bad struts/shocks, so it could be that. You have struts on the rear axle, and the ‘bounce test’ doesn’t do a good job of judging their condition because they have lots more internal friction than a shock. So you may need struts. Also make sure the rear suspension bushings are in good shape. Unevenly worn tires would have to be real bad to cause this, I would think. But if they’re worn badly, replace them when you get the struts.

Your mechanic has it backwards. You have it correct. The tires wearing unevenly are probably caused by worn suspension components, probably the struts. The old “bounce test” really is not a good indication of their condition. Hopping around on a bumpy road is. ’

Try a good chassis shop.

Well, after 60K the tires certainly are suspect. Rear struts don’t generally have to work too hard, and last in most cars for a couple of hundred thousand miles. Unless you have been hauling around a lot of weight in your trunk, I bet your rear suspension is fine.

Drive tires wear faster than any other tire. But there are few tires that last much longer than 60K. I bet you have old, worn tires and should replace them, all four of them.

The OP said he had only 20K on the tires not 60K. Struts can be worn to reduce effectiveness at 50K so I think you need some struts.

Bad suspension leads to bad tires.

Have your suspension checked over by another mechanic/shop. Beyond the struts you could have worn bushings or other suspension items.

Most rear struts do last longer than 60k but all bets are off with 7 years. The joys of an elder car…

What pressure are your rear tires inflated to?
Does the car react differently to the same road if you place between 50 to 150 lbs of weight in the trunk? (got a nephew? Stuff him in the trunk!)

Its most likely going to be a combination of things.

If the tires are wearing funny in the rear of the car, then you are in need of a full 4 wheel alignment. This alone might bring the car back into normal behavior.

Its also possible that the cause is a bad strut in the rear, that has leaked out all the oil. Easy way to tell this it to have someone drive your car down a bumpy road, with you following behind, and watching to see how many times the tire bounces after hitting the bump.

It should go up, then down, and then the car should be settled again. If it bounces multiple times after hitting one bump, that strut is bad. I see cars doing this all the time, and wonder how the driver doesn’t know something is wrong with their car.

And if the tires are not worn evenly along the tread, then the tires will need to be replaced after the alignment is corrected.

But you should get the car over to an alignment shop, for a full inspection of the rear.