I have 225/45/18 on my stock 04 rx8 rims will 225/40/18 fit? Thanks in advanced guys.

 

Yes, the 225/40/18s will fit your stock rims but your speedo will be reading higher than your actual speed because you have effectively reduced the diameter of your wheel.

http://www.paspeedo.com/calculator.htm for more info.

 

try 245-40-18's

 

I concur. Even with a little drop (Tein s-tech) the tires fit fine. 225/40... What drives your desire to go to a shorter tire?

 

+1 THE 245x40 are the best upgrade. Some have pushed it to 275X35, but with a few problems and more $$ why? Here is a site to help you with the size and how much it will change your speedometer. Put orig on left and change size on the right side. Then look at differences and then speed variance on bottom.


http://www.miata.net/garage/tirecalc.html

 

yeah i have the 245 40 18's and they are nice i mean if you're already dropping the sidewall height y no tmake them wider also?

 

I got 225/40-18 on my 8. Even with the Tein S springs the tires are just inside the fenders.

Why? A lighter tire and a little lower gear ratio cant hurt. I speedo is only off by 3mph(I drive by a posted speed trap every day).

 

so apparently the closest fit in a wider tire is actually a 255/40/8.

that will fit on a stock rim too. not ideal for 8" wide rim, but it'll fit.