I'm not looking to get bagged one or anything, but I have been trying to find out what the damn numbers mean on the tires and rims. Basically all I want to know is if I can get 18" rims that are 8" wide or is 7.5" as big as I can go without rubbing. and yes I plan on lowering my car in the future(god knows how long) and will that affect it? Any help would be greatly appreciated. THANKS!!!

 

I believe there are a couple members who are running 8" wide rims. You will need new tires though.

 

I work at a Costco Tire Center and at work we have a plus sizing guide for what will fit on vehicles. At stock height, the cobalt SS/sc will fit a 245/35R18 it will be about .54" taller than stock, meaning that the speedo will show 60mph when you're going 58.6mph.

As for the rim size being 8", that is the minimum width for a 245/35R18.

 

tirerack.com has great articles on tire width
here is a site to figure out how far off other tires will be
http://www.miata.net/garage/tirecalc.html

 

If I lower my car will they still fit?

 

your leaving out the part about having to have the right offset as well

 

Your right for the speedo actually, just the 245/35/18 tire will be smaller by .54 and not taller.*

 

^^ my bad, my bad. shorter not taller, and 35-45 offset. 40 should be perfect.

Yes it should fit with your car lowered. But just take it easy on turns in the beginning and slowly increase the degree of the turn and the speed at which you are travelling. That will increase body roll (if there is any), but gradually that way if you do hear it catch you can ease out of the turn radius.

I did that with my 69 GTO. It originally had something like 215/70R14 (translated from the letter sizing), and now I have 295/50R15 rear, and 245/65R14 front. I did rub a little bit, so I got out the old block of wood and a hammer and tapped in the sharp corners.

 

Thanks for the help guys, it was great info. Thanks again.