why a 40 profile for 18's not a 45?
 

i know a 40 profile tire is recommended for 18's but the roads here are extremly bad..and i really want a 45 profile tire..but im also getting a 1.7F 1.5R drop..is this a bad idea? it might rub

thanks guys

edit:i know it might mess up your speedometer but will it mess it up by a WHOLE lot or just a little?

Should be fine but 45s are less popular than 40 and may be more expensive.

Depending on the width it will be a slightly larger tire that should not change your spedo more than a few mph.

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

1.3% too slow instead of 1.3% too fast for 235/45-18 versus 235/40-18.


235/45-18 has a diameter of 26.3 inches
235/40-18 has a diameter of 25.4 inches
225/50-17 has a diameter of 25.9 inches

i have 235-40-18 on 350z wheels, i love em they ride smoother than stock

A nice tire size that I found works real nice is a 225/45zr-18. You can get continental for about $150 tire or avontech which has great ratings for $130 a skin. I'm a big advaocate of the 45 profile tire because I live In Rhode Island and the roads are terrible.

why would you want 225s? Unless it's strictly snow reason

the 235/40 -18 is'nt even that small of a profile. I live in Connecticut and the roads are awfull. I was actually shocked at how smooth of a ride they were; the michellen pilots help. Just got to watch out for those pot holes.

a 45 profile tire may or may not be larger than a 40 profile.

Rember the profile is a ratio so a wider tire will have a taller profile even if the are both 40.