Topic: Cupping tires: do I need new shocks?

[boz]

Hi,

The dunlops at the rear on my 03 Toyota Matrix (just over 178k Kms) are cupping in the inside. Outside probably has more than 6mm tread without any cupping, but inside is badly cupped, making a lot of noise and going to be bald soon. I've been told to replace my shocks&tires by a shop along with a bunch of other stuff, however an another shop recommended replacing tires only without commenting on anything else.

Would you say it's about time/mileage for new shocks or should I invest in two used tires ($100) first to see if they would cup as well before spending $500 on new shocks. 

[rrocket]

Probably wouldn't hurt to have new shocks+alignment

[capriracer]

The term "Cupping" is frequently mis-used. 

Technically, shocks or an out-of-balance condition causes cupping, but the term is also used to describe wear conditions caused by mis-alignment - and that's what is being described in this post.  So an alignment is called for.

Just be aware that many vehicles have alignment specs designed for good handling - lots of camber - and that's not good for even tire wear.  Anything over a degree is suspect!

Also, the published alignment specs have tolerances that are way too wide to insure good tire wear.  In particular, toe has to be within the inner half of the spec.

[HeliDriver]

Whether or not it has anything to do with your tire wear, I can't believe that shocks with 178,000 kms on them aren't well past due for replacement.