im getting cobra r's with 255/40's. i am gonna roll my fenders and run 1 inch spacers all around? will i still have any rubbing issues?

 

On a 66....yes.

They won't fit the front and they will rub in the rear unless you roll the rear fender.

 

Will they rub because of the width? Those tires on 17 inch rims is still an inch shorter (diameter) then what I have on my front (235/60/15) and 2 inches smaller then what I have on the rear (same width). Heres a pic of rear

 

IMO dont put cobra r's on classic mustangs, especially the pony cars 64-66. get some cragars or american racing wheels that go with the age of the car

 

I run 255 40 in the rear on my 65, fenders are rolled and they still occasionally make noise.
I run 245 40 in the front I don't rub, but I also run 2.5-3 degrees of negative camber, most people don't and many claim to occasionally rub with 235s.

 

so i would be fine if i run a 17x9 wheel out back with a 255/45 tire. or should the rear be a 255/40? (profile)

and i would also be fine to run a 17x8 wheel up front with 235/40. or should i run a 225/40 up front? (width)

 

I doubt a 17x9 will work for you. The 255 40 fits nicely on a 17x8 wheel however and fits both the car and the rim. 255 45 is a generally a little taller than a stock mustang tire and a 255 40 is generally a little shorter than a stock mustang tire but closer to stock size than the larger one. If I can get them to rub occasionally even with the fender lip rolled I would expect the larger tire to rub more.

My originaly combination was a 235 45 17 and a 255 40 17 in the rear; which gave me a front tire that was just slightly larger than the rear. I now run a 245 40 17 in the front and don't have that problem anymore. Personally unless you are driving a fire breathing monster (like I do) I would run a 245 45 17 in the rear and a 235 45 17 in the front, or even 235 45 17 all the way around so you can rotate if you want to.

 

well im building a 331 stroker with 400+ hp so that will be going in soon. i dont know if you want to call that a fire breathing monster...but its probably close. so i would be good with a 245/45 in the rear and a 235/40 in the front..am i correct? or should it be 45 series all the way around? (which would be 245/45 rear, 234/45 front)

Multiple Choice:
[ul][*]A. 245/45 Rear 235/45 Front[*]B. 245/45 Rear 235/40 Front[/ul]which is best?

im just trying to be very clear and specific about this. i just wanna know what would be the max size i could have is without MAJOR rubbing. thanks

 

The max IME are:

245 40 17 in the front with:
shelby drop, 3 degrees negative camber, 620 drop springs, roller perches, adjustable strut rods, ias shocks

235 45 17 in the front with:
shelby drop, 1 degrees negative camber, 620 drop springs, roller perches, adjustable strut rods, ias shocks

255 40 17 in the rear with:
Rolled lip, 5 leaf mid eye springs, kyb gas-a-just shocks, watts link (prior to the watts I used to get significant side to side deflection so when cornering at speed and hitting a bump I would rub bad)

245 45 17 in the rear with:
Rolled lip, any leafs, any shocks

Again, IME (in my experience) all tires mounted on a 17x8 with 4.75 backspacing.
So that would make me choose 'A'

 

ill go with a 245/45 17x8 rear. now how about this...17x7 225/45 front?