The 2005 GTs come with 17x8 rims with P235/55ZR17 tires. I was thinking of going with some 18x9 rims when I get my '05. What size tire would I need in order to keep the same diameter so I don't mess up the spedometer? Is there a formula or trick to finding it out? Thanks.

 

Another question. does anyone know of a website where you can see wheels on the new Mustang? I know discounttire.com has a tool to do it, but was curious if anyone knew of more.

 

i know tirerack.com does i am not sure about on an 05 tho.

 

How big of a tire can you go on that stock rim I like to know. I like to have that tire just a little bit bigger but again will this mess up the speedmeter?

 

Here are 2 sites that have tire size calculators, the second one is best IMO.
http://www.miata.net/garage/tirecalc.html
http://www.1010tires.com/TireSizeCalculator.asp
Also, tirerack.com does have the 2005 in there, you can even choose the color.
http://www.tirerack.com/upgrade_gara...5&autoModClar=
Lastly, according to all tire spec charts I have found, the maximum tire section width for a 7.5 inch rim is 235, in my experience as a tire installer, you can safely (in most cases) add .5 inch, doing that would allow up to a 255. You could run a 255/50/17 (it's 3/4 inch wider than stock) with little worry, they would make your speedo read 60.3mph when you're going 60mph, so not much different.

Hope that helps.

 

Thanks for the info. am1scott