im looking at some 245/45/18 not to sure it that would look funny on stock 18s and its lowered on s-techs, http://www.tirerack.com/tires/tires....e1=yes&place=0

 

I'd go with 245/40/18

 

yeah but it will show more of a gap, and look smaller i think 40 and 45s is noticeable?i don't mean to thread crap but i really not to sure on the tires i need, and i do drive hard, and i don't want to gain anymore gap in the wheel walls.

 

245/40 is what you seek.

Overall diameter is better and as such, your speedometer won't be off by as much.
http://www.miata.net/garage/tirecalc.html

 

I can't imagine you have too much gap on s-techs.

 

i can fit 2 fingers in the front and back, i dont want to fit 3 fingers on the 40 series, maybe i should preload more..i got the springs installed last saturday and i went home and peloaded, it went down alot in 5 min lol

 

+1

The 245/45's are actually taller than the stock 225/45's! They are taller than the 245/40's are shorter (if that made any sense)

Outer Diameters
225/45 - 25.97 in
245/45 - 26.68 in
245/40 - 25.71 in

The exact diameter is really dependent of type/brand of tire but those differences are negligible. You can get the idea from those numbers posted above. Remember, tire profile is not a straight number, it is an algorithm that takes into consideration tire width.

 

thats crazy that the 245/45 is taller then 225/45

 

um no - not actually . That is how tyre sizing works .

the 45 number is the tyre profile which is a % of the width .....

 

i have a set of dunlop star specs that are just broken in.. they have 5 track days and about 8k miles on them..

they are 245 40 18. you worry to much about this gap.. sounds like you need coilovers more..

beers