I just bought a set of four 18" X 7.5 rims. Anyone know what tire size best fits them? I have 235/40 zr 18" in mind but don't know if that's the best tire size for these rims... thanks.

 

Yes, you are correct. For 18" x 7.5 you will need to get the 235/40/18 tires. Now I'm sure that you could go lower than that but probably not by much. I just ordered some 18's with the same kind of tires and I can't wait to get them on my car. It will look nice. Have fun!

Shadou

 

I just checked a few tire websites (Nitto, Toyo, tirerack, etc). It seems that 235/40/18 requires a minimum rim width of X8 So to be on the safe side, I would need to get either 225/40/18 or 225/45/18

Shadou, or anyone... care to comment? thanks

 

No no No, for the best tire size and the most accurate speedometer reading, a 245/40/18 is the right size, this will only show the speedo about .55% too fast, where as if you choose the 235/40/18 then the speedo would be 1.77% too fast.

And YES a 245 tire will fit a 7.5" rim width.

 

235 should be fine on 7.5" rims.... Even 245 may be ok, but it depends on what the tire manufacturer states..... follow those guidelines

 

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



I used 225/40ZR/18 on my 18 x 7.5