255/40-17 or no?

maddmatt

New Member
Nov 10, 2008
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I have a 92fox about to put on some 99-04 mustang gt wheels 17x8 need to buy tires. Will 255/40-17 fit? I will be using the car in alot of auto cross so I really need to be able to turn lock to lock with no rubbing. The car is 1.5 lower plus what ever 98 mustang spindles add if any to lower it.
 
What size up front can I run that will not rub?

tires arent going to be the issue, but the offset on the wheels might be. the 98 spindles you have pushed the front track out past where the stock spindles would put it, which usually puts the tire right under the fender lip. this is why most people recommend the 94/95 spindles, because the change in track width is (relatively) much less.

iirc, 05+ wheels will have the correct offset to be able to pull the wheels in enough to minimize the chance of rubbing, that being said though, if you already have the 17x8's, they may be narrow enough to work, but i'd test fit them to make sure.
 
Correct. It's the spindles which push the wheel outwards more creating a larger arc the wheel sweeps through when you turn. You need a wheel with a deeper offset to pull it back in.

But 94-95 spindles will tuck in 8mm more than the 96+ spindles, and create a smaller turning arc for the front wheels.

I have Sn95 17x8's with 245/45/17 and only have rub at full lock...like making a u-turn. I run the 94-95 front spindles.
 
I say no and here is my reason. A 255 tire is too big for a 8" wide wheel, just about all brands of tires that are 255 are for a 8.5" to a 10" wide wheel. Now I know the 1st thing that is going to be said is that you can still mount it on a 8" wheel and it's true but the problem is sidewall bulge and how the tread contact patch is affected. If you want to autocross the most important item is going to be the tires and the contact patch and how the sidewall is going to control it has well as heat build up in the side wall from to much flex, etc. It's no different than taking a 225 tire and streching it across a large dia wheel like a 9 or 10" it looks like a basket ball.

The tire you reall need for a 8" wheel to keep the sidewall straight so the tire an do it's job is something like a 245/45 or a 235/45 which will be close to the same dia has the 255/40. I have 255/40-17's all around on my stang but I have 8.5" wide wheels, the fronts rub on full lock but it's more due to the width and offset of the wheels. I'm changing wheels in the spring to a 17x8, 17x9 combo and will run 235/45 up front on the 8" and 255/40 on the rear 9". hope this helps but it's my opinion that the 255 will be too big for your wheel if you want the most life and handling out of your tires.
 
I have the same size tires on the front and rear on my 92 coupe with the Eibach Pro kit springs, I'm using 17x8.5 wheels all around. The only rubbing I get is with the rim touching the jacking plate on the lower control arm. I heard that 92 and 93's have a slightly different fender......
 
A 255 tire is too big for a 8" wide wheel, just about all brands of tires that are 255 are for a 8.5" to a 10" wide wheel.

Ford did it.

1994 and 1995 Cobra came with 17x8 wheels and 255/45/17 tires.

They way i've heard it, the max you want to go over rim diameter is 2". SO on an 8" rim, you could go 10" wide...which is 254mm.

But a 255/40 will have no sidewall and a good size bulge to it. But i'd have no prob running a 255/45
 
I have a 92fox about to put on some 99-04 mustang gt wheels 17x8 need to buy tires. Will 255/40-17 fit? I will be using the car in alot of auto cross so I really need to be able to turn lock to lock with no rubbing. The car is 1.5 lower plus what ever 98 mustang spindles add if any to lower it.

I'm by no means an autocross expert, but when during autocross racing do you turn lock to lock?
 
Last time out wiht my '03GT, there were some good sharp turns on the autoX course i was on, but i can distinctly remember driving with both hands on the wheel in 2nd and never really going more than 1 full turn in each direction.
 
I only rub with 245/45/17 at full lock, and i have the smaller '88 fenders. Unless you are lock to lock, you should be okay.

Got a friend with some wheens you can test fit?
 
Ford did it.

1994 and 1995 Cobra came with 17x8 wheels and 255/45/17 tires.

They way i've heard it, the max you want to go over rim diameter is 2". SO on an 8" rim, you could go 10" wide...which is 254mm.

But a 255/40 will have no sidewall and a good size bulge to it. But i'd have no prob running a 255/45

A 255/45 tire is designed for a 8"-9.5" wheel going by most tire companies. The 255/40 tire is designed for a 8.5" - 10" wheel ..don't forget about the aspect ratio.
 
A 255/45 tire is designed for a 8"-9.5" wheel going by most tire companies. The 255/40 tire is designed for a 8.5" - 10" wheel ..don't forget about the aspect ratio.


Oh tire companies don't know what they are talking about. :lol:

DSC_0146-vi.jpg




Just kidding of course. :)
 
Oh tire companies don't know what they are talking about. :lol:

DSC_0146-vi.jpg




Just kidding of course. :)

That car has the right size tire... wrong wheel. If you look the tire fits in the well. If that moron put the right size tire for the wheel on there it would rub. But what I really want to know is, how the hell do you put those on your car and go "Damn, that looks SWEET!" I would bet money, if there's a more recent pic of that car, the lip would be all f'ed up from curb shots.