Whats the largest tire I can fit on the stock 18 inch rims?

 

Just for clarification...

By largest tire, you mean widest tire?

 

yeah. my bad

the 235's will not be good enough in a week. infact they are kinda lacking now.

 

What's the width of the rim on these 18's ?

 

It depends on the width of the rim. THe rims shown in the picture are 8" wide, the widest that you should go on such a rim is 245. You can put wider tires on the rims, but you're going to get an irregular wear pattern because the contact patch is going to be off. Check this site out, they have a really good size comparison application.

www.rimsntires.com

 

I guess I have to buy a new set of rims

 

The original tire size should be 235/50-18 on your stock 18x8 wheels. A fairly common "Plus Zero" upgrade that easily fit would be to a 255/45-18, which is 20mm wider (nearly an inch) but the same overall diameter, so your speedometer won't change.

 

Really? Then why do tire manufacturers in general list an 18x8 wheel as in the acceptable range for a 255/45-18 tire? Heck, if you go to the very site you give a link to and type in the 255/45-18 size, they list "18x7.5 to 18x9.5" as the acceptable wheel sizes for that size tire, and if you've been searching under the 2010 Mustang GT, they say "Correct size for Mustang GT" beside the 255/45-18 tire.

 

I am looking for 285 or larger so they are out either way.

 

You need 9.5" to go 285's all the way around. Or you can stagger and go with a 10"+ rear and get 285+

 

this is what im thinking http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT

I can pick them up next weekend. they quoted me $400 for powder coating

 

From the add...
I don't think those tire sizes are correct. They should be 255/45/18 front and 285/40/18 rear.

 

agreed.

 

255/45/18 will work easily on the 8" rim, will only be SLIGHTLY wider tire than recommended, 285 is out of the question.

 

To run, 285/40/18 your rim will have to be 9.5-11 inches...

 

thats why im buying different rims

 

There are a number of autocrossers running 295/30-18 tires on stock Shelby GT sized 18x8.5" wheels, but they are race tires (Hoosier A6's) and it is only because the class (F Stock) requires you to keep the same height and width wheels as stock. Wouldn't recommend going that extreme for street tires.