Autocross Tire Size Decisions, Decisions, Decisions...

I am running a 2011 Mustang V6 in DS. I want to stay with the OEM 17x7 size wheel. Lord knows I'd prefer to run 18x8's, which are legal, but that shoots tire prices out of my range.

My question is, staying with the OEM 17x7 and according to the rules I can use any size tire that will fit, what tire size do y'all recommend?

If it matters, I've partially retrofited the Premium Performance Package, i.e. Boss 302 front strut bar and GT500 rear lower control arms with near future plans for GT front sway and enlarging the lower strut hole for collision adjust camber bolts.

Edit. Almost forgot most important info: OEM tire size is 225/60 17.

Eyethanque.

225/45/17 seems horrifically undersized for such a heavy car. But anything wider is going to be pinched on a wheel that narrow.

I think I'd really consider the 18" option and get some proper-sized "2nd tier" tires (Federal or GT Radial-Champiro SX2 etc.) to keep costs in check.  Anything above a 225 will be pinched on a 7", whereas 255-255 on an 8" will be fine. 

Yeah, I'm with FSP_ZX2. Save your money and get the wider wheels and a cheaper tire, like the Fed RSRR, the Nexen Surg4 whatever it's called.

A 7" wheel is fine for something sub-3000, but not for your car. Heck, I had 7.5s on my 3100 lb E36 with THE top tire at time in a 225 size, and it was abysmal for autocross. The car worked SO much better with 9s all around.

You might even be able to find something used in that 225-255 size range.

Wow! I did not know about those brands! What a bargain.

So you're saying 255 on 18x8's. Should I bump down to 40?

Thanks.

phaze1todd said:

Wow! I did not know about those brands! What a bargain.

So you're saying 255 on 18x8's. Should I bump down to 40?

Thanks.

If you mean 255/40/18 vs 255/45/18, then yes.  Check the diameter of your existing tires, compare to your top speed in 2nd gear and decide if you want to trade speed for acceleration, or acceleration for speed.

In stock form, you have tall tires (27.6") and tall gears (2.73). Unless you swap out for the 3.31 rear end from the performance pack, there is no such thing as too short of tires from a 2nd gear autox speeds perspective. Stock has something like an 80mph top speed in 2nd, and even a 225/45R17 would top out at 72mph. Then again, the good performance tire sizes for a 17, or even 18 inch, wheel size will look absolutely ridiculous under those fenders.

Ultimately, yes go with 18's if you can. If these are street use, I'd probably look for a 245/45R18 or 255/45R18 to keep it from looking too goofy.  If these are for autox only and you don't care about looks, perhaps more like a 245/40R18.

245/40/18 falken rt660s are the same price as most other 225/17s. Best of both worlds, cheap and actually competitive unlike the federal and GT garbage. And probably better wear from not overworking the tire as much versus the 17s so cheaper long term aside from the wheel purchase.

As far as general sizing advice, I don't know much about the mustang but I know they're relatively heavy strut cars and I assume at least somewhat limited on camber. If that's the case I wouldn't want to go wider than 225 on a 7" wheel or 245 on an 8".

In reply to dps214 :

Camber can be made adjustable by up to 2 degrees under "collision" standards.

If you decide to go with the 595 RSRRs from Federal, just know that they are stupid noisy on the road. Like 4x4 mud grip noisy. 

They make RE71Rs seem quiet. 

I wouldn't want to DD them but have been very happy with their performance and wear.