ezio350

Have an '07 GT. Came with the Bullit 17 inches. I had the dealer swap me out to 18's, which was part of the deal. 4 days later I put them on. Oh my gosh. Bad mistake ! the 18's look beautiful, but they slow the car down quite a bit. Noticiable !!!!! I then learned that the 18's are 30.5lbs a piece and the 17's are 21.3lbs. a piece minus the -.3 inch overall diameter. Needless to say the 17's went back on the car. The difference is night and day. Tire pressure was 35psi all tires. Point is, the 18's look awsome, but will hurt your Mustang's acceleration where you notice it right away. If you have 18's, give it try. Test drive a GT with 17's.

WhoMe

My car is coming with 17s but will be replaced with 19s. Itl be interesting to see what that does to my acceleration. Thanks for the story.

Mellowdien

i'm riding on 20's lol....compensated with a cai and tune
never drivin' a stang on 17's before...i want to though
don't think it's gonna be THAT big of a difference, cuz my worst g-tech was 14.2 sec.
and my best 13.7

CrazyAl

This also depends on exactly what wheels you have. Keep in mind that not all 17s are 21 lbs and not all 18s are 30.5. lbs. And in some cases an 18" tire is lighter than a 17" tire. But definatley the point is true: heavier wheels = slower car.

tg5spd

Interesting...I was wondering about this. I've got stock 18's and was considering getting a set of 17's (oem pulloffs) for track days. I'm sure the speedo would be off, not a big concern. I'm wondering if the 18's have better traction than 17's due to more tire hitting the road.I also wonder which are lighter,the 17" bullits or the 17" oem aluminum upgrade wheels?

modular81

I have a set of machined aluminum 17's with the pirelli tires setting in my garage. On my next track day i going to swap them out and see if this helps lower my et's. I drove a gt with the stock 17's and one with the stock 18's and the 17's did make a difference in acceleration, the rear tires just seemed as if they turning over faster than with the 18's. Both gt's had 3.55 gears and were 06's. Hopefully this will help a little in my quest for 12.90's on stock wheels and tires.

ezio350

true on which type of wheels. But OEM Vs. OEM the diff. is huge. My wife's '07 w/18, CAI and no spare ran side by side with my '07 w/17's no mod and spare in the trunk. these were 2nd-3rd gear pulls. She is a good driver too. 13.9 at 100mph on her 5spd. Now, if you are autocrossing, the lower profile on the 18's will give you better handling, as far as acceleration no.

jrm1900

I agree with your comment, Idont know the physics or regulations behind it, but out of pure observation, dragsters run higher profile tires while circuit cars are the opposite, I guess if you run circuit you want to avoid tire sidewall deflection to improve cornering and g'swhile at the drag strip you just need forward traction. However each tire has its own characteristics that define its performance under specific circumstances, like rubber compound, thread design, steel reinforcment etc

jas451

I just swapped 17" Bullits for the OEM 18" polished Bullits. I could swear I read
the specs that the 17's weigh in @ 25 #'s and the 18's @ about 28 #'s. I knew
I was going to gain a little weight but I figured the appearance was worth it.
I think that the Steedas are considered light weight and they weigh in @ 25.

moosestang

I weighed my stock 17's on my bathroom scale. They weighed 50lbs. The stock tires weigh 28lbs according to tirerack.com's specs for the pirellis, so 21.8lbs is probably correct.