I just got my Z. I have two sets of wheels/tires for it. One set was 18" Kazeras with winters, and the other set is 19" volks with proxies.

I bought the car with the kazeras on it and it drove perfectly. No shim or vibration even well above 100mph.

Last night I put the volk/proxies on it and there is a shim in the wheel. It's noticeable over 30mph. The proxies are the t1r and are brand new

Does this seem like a balance issue or tire issue. I'm going to get it taken care of asap, but I'm just wondering what you guys think. Thanks.

BTW, I torqued the lugs to 83lbs. each, so they aren't over/under tightened.

 

Did you install hubcentric rings?

 

sounds like a tire balance issue or above ^^

 

^^ what these guys said. If you can confirm that you installed hubcentric rings, then take it to your trusted wheel/tire shop and have all of the wheel/tires checked for unbalance.

 

It was the rings. I completely forgot about them. Put them on tonight and the car is 100% stable. No shim. Thanks for the quick replies.