Rims/tire Sizing

[natedawg9640]

k so i found a set of 18's.... now i wanna know what size tires i need to find... i dunno how they catagorize sizing so i dunno how to look it up... i tried the search feature and didn't get much out of it.... so anyway... they are 18's 7.5 wide.... what kind of tire am i looking for... lowpro but not flat or nothin...

[gre0481]

you're going to want to throw on 225/40/18's

Maybe 235, the wider you go, the more risk of rubbing. 225 is working great on mine; good traction booster.

40, because anything higher ie, 45, 50, will throw off your speedo too much. That could throw off some of the stuff in your cars chip programming.

225/40/18 gives you the same tire diameter as stock. (as close as yuou can get to it; talking fractions)

I love my Toyos proxes 4's, which run about 150 to 160 USD. Their are cheaper alternatives, but toyo are high performance. More bang for the buck that a BF goodrich GFORCE.

Good luck

[Youngblood77]

Here you go, fellas......don't say I never gave you anything. :cool: All you need to purchase the right tire size can be found right here. (http://www.miata.net/garage/tirecalc.html) Just make sure you know the vehicle's stock sneaker size, and you're good to go. :thumb:

[gre0481]

Yeah, the miata site. Saw that in another thread.


So 225/40/18's is 0.3% faster on your speedo. That's comparing with 215/60/15's.


The difference between 225/50/16's is a bigger difference.


If you compare the 15" stcokers to the 16" stockers; the 16" stockers roll 1.2 % faster than the 15's.


SO if you look at it, .3% is less notcieable than the difference between 16's and 15's.

Warning though, the thinner you go on tires, the more road hum you'll hear.

this also depends on Tire pressure. You'll want to run higher pressure than the 30 recommended by the dot label on your driver door.

I run between 45 and 50. Your tires flex more when the pressur is lower.
More flex means less protection on your rims. RUnning higher lessons the chances of flexing, and bottom out your rim. SOmeone else could probably explain it better than I did. Hope it points you in the right direction

[FormulaNERD]

if you're running 50 psi you're probably going to see premature wear in the center of your tire. you'll have better traction in both straight away, and corners if you lower your tire pressure closer to 35psi or so.

[AlbinoMonkeyRat]

^ tru dat. 32 to 40 psi is good for everyday driving; 26 to 30 psi is good for the drive wheels on drag. 50 psi is usually way too much on cars.

[gre0481]

ah, SO not much benefit to protect the rim?

[AlbinoMonkeyRat]

the best way to protect the rim is to not drive into curbs, and KNOW where the pot-holes are. Also, you might want to consider getting some low-dust brake pads, especially if you want to keep them shiny.