70 Mach I rear tire width

[Nemesis67]

Just picked up a 70 Mach I...
How wide of a tire can I run under the rear without any modifications other than the fender lip rolled and the rear rims are 17"x9 (ballpark)? I plan on using a negative offset as well. I hear that I can go as wide as 275mm.
Thanks everyone!

 

[2+2GT]

Mustang Wheel and Tyre Chart

 

[Grabber70Mach]

http://www.dodgestang.com/Tire Fitment Guide 69-70.pdf

or

70 Mach 1- How wide can you go?

 

[lauras70mach1]

I have 275/40/17 on the back of my '69, 17x9 wheels.

 

[Nemesis67]

I have 275/40/17 on the back of my '69, 17x9 wheels.

What is the backspace and offset if any on your 17x9 wheels?

 

[lauras70mach1]

VINTAGE WHEEL WORKS WHEEL 17X9 VINTAGE 40 1965-1973 - CJ Pony Parts, Inc.

 

[4MuscleMachines]

I have a 18x10 with a 295/35/18 KDW tires on rolled lips and those are wider tires than normal for that size. You can do it if you nail the backspacing and your spring bushings are tight, preferably with those offered by Global West and such.

 

[Young Gun]

Just like 4 said, if you nail the offset and backspacing, you can get a big tire in there and also have it look pretty good. I have a 67 coupe wih 17x9 rims and 275/50/17 tire. The tire doesnt stick out the finder lip either. So it is possible. What I did, and maybe possible for you is, go to a tire and rim company and ask if you can do a fitment appointment. It only cost me about 20 bucks and I tried on about 4 different rims and like 10 tire sizes.