My Z came with a brand new set of AV100 tires, they stick ready good but when going over 70mph the steering wheel gets a little shaky. I took a look at the rims and the wieghts were removed from all 4. Is it a balance issue or a tire issue?

 

get them balanced.

 

Couldn't have said it better myself. Preferably on a Hunter Road Force balancer since it happens over 70 mph.