[kalrith]

I guess this question could be applicable to any car, but I'm asking it specifically in regards to a 2008 Mustang GT, which is hopefully in my near future. I would like to get low-profile tires for the Mustang, but I don't want to go larger than 18" rims because of the extra weight.

So, what would be the potential problems with going with say a 255/35/18 tire on all four rims? This would be 25.02 inches in diameter, rather than the stock 27.3 (I think). I would get the speedometer recalibrated, so that's a non-issue. stlwagon went with larger diameter tires and said that it made his axle ratio act like a lower one. Would smaller diameter tires make the stock 3.55 ratio act like a higher one?

This is just a question I've had for a while for which I haven't found a good answer. I thought you guys (and gals) might be able to help me out.

Thanks!

[exospawn]

Not sure about the mechanical issues it could or could not present, but i can tell you I have 18" rims w/ 255/45/18 on them and there is alot of rear wheel well left.

That's the main reason I'm thinking about going to 20" just to take up some of that slack, I can't lower my car with the Cervini kit and side exhaust, I only have 3.25" not at the lowest bracket.

[kalrith]

I'm not sure how it would look with the smaller tires on there. That is a concern of mine, but I'm mainly looking at it from a performance standpoint. I do know that it should lower the car about 1.14 inches, which is the difference in the radius between the stock tires and 255/35/18 tires.

If you get 20" rims but try to stay with the same tire diameter, it actually won't fill the wheel wells any more than your current tires. The larger rims might make it look like that though.

[Stoenr]

I wouldn't do it. It would look funny. Handling will be sacrificed, and that small of a tire would have a much lower load capacity.

[haropr55]

Tire diameter = mph x gear ratio x 336 Rpm

Gear ratio = rpm x tire diameter Mph x 336

Mph = rpm x tire diameterGear ratio x 336