hmkim

I had Costco replace the worn out stock tires with the same ones (Michelin Energy 17") for my '06 ES330 (39k miles).

I am not sure if I'm imaging it but it seems that the steering wheel vibrates at high speeds more than it used to. The vibration isn't bad at all but I don't think I noticed such vibration before.

Is it something associated with brand new tires? Or did the shop fail to properly balance them?

GoodRevs

Sounds like you need a wheel alignment

BDSL

Before you doing anything else, you should check that all lug nuts are tight. Then get Costco to check the balance. They should re-balance at no cost.

mkeeney

Do what the other posters suggested. It could just be tires with poor uniformity also. Keep in mind that the auto manufacturers get the very best tires for OEM use. There are generally two standards for tire uniformity - OE and aftermarket. If you buy the same tire model that is used on your car new, you have a lower chance of getting great tires as replacements because the lower-quality tires are reserved for aftermarket. This is why I recommend that you never buy a replacement tire that is also used as original equipment.

If Costco can't satisfy you with the above suggestions, make them replace the suspect tire(s).