Tires vs Rim Size

[jwlast]

Question for the group. I’ve got a 06 GT with a 62mm Hellion turbo at 9 pounds of boost. Dyno recently at 470 HP and 500 lbs torque. Car is bone stock except for the turbo. Got mods gonna be bolted on in the next couple weeks (MGW shortthrow shifter, line lock, etc) but looking at tires as the next major upgrade.
Car has the 18 x 8.5 wheel upgrade from Ford with the 235 BF Goodrich tires. These tires aren’t even close to be able to handle the cars horsepower. So, after exhaustive research have decided to go with MT ET Street Radials II. Based on what I’ve seen on the MT website the biggest tire this rim size can handle is the 245, but I’m thinking the cars horsepower will bust the 245s loose. Now they do list a 265 width, but the recommended rim size is 9-10, but mine are only 8.5s. What are the risks of running the 265s on 8.5 inch rims? Tires will be bolted on prior to going to the track, raced, driven home, then stock BFG put back on. Any help is appreciated.

 

[Chris06GT]

jw, first off welcome to the site!!!

There are a few guys on the forum running the 265/40's on stock 8.5 rims....I'll see if I can get a few of them to chime in....maybe with some pics as well....

Also, use the search, I think there are still a few threads lingering around discussing the 18" tire capabilities.....

Chris

 

[stkjock]

I run those tires 24/7/365, they hook well on the street and I've pulled 1.68 60' times with them at the track. The other choice in tire is the M&H 275/45/18 that a few guys run as well, it has much more sidewall and is 28" tall vs the MT 26.4".

Here are a few shots of mine:

And at the track:

 

[rojizostang]

i run the mickey thompson et street radials 265/40/18 on the 8.5. no problem, but no pics right now either. i've cut a best 6o' of 1.84....but that's more a driver issue than a tire issue, i mean it should do a lot better