I'm about to get my G35 18's in the mail and had a few questions about it... First off, I know changing the tire size/diameter will offset the speedometer, but is this change determined by the size of the front wheels (in FWD)? My 18's will have the stock tire sizes, 225/45/18 front and 245/45/18 rear. Another question... Will I need new lugnuts (boy, that sounds like a dumb question)? Thanks!

 

It all depends on the tire size. Check out miata.net's tire size calculator and punch in your before and after tire size and see how much difference it makes.

 

I understand that, I'm just wondering if the difference in the speed is determined by the size of the driving tires (in my case, front for FWD).

 

Yes, your drive wheel tire size will affect your speedometer.

 

^ Thanks! That's what I thought.

 

waht size tire do u plan on running

 

the 225/45/18 will have a 26" diameter, not sure what your stock tire size is. Use this http://www.eunos.com/tirecalc/

 

I'll be running the G35 stock tire size, 225/45/18 in the front and 245/45/18 in the rear, as I said in my first post. According to the Miata Tire Size calculator, my speedometer will be off by 2.6% (too slow). My stock tire sie is 215/55/16. I already knew all this, but am still wondering if my regular lugs will fit OK, though (I'll find out in a few days when I mount them, regardless).

 

Do you have pic's of the wheels? if you have a good pic i could probably determine what kind of lug.

 

Nevermind about the lugs... I got my question answered. FInally just mounted them and the ones I have will work fine, but I'll probably get some longer lugs off ebay.