what is the widest tire i can put on the rearson my 69 mach 1? without doing any modifications.

 

Depends on the backspacing of the wheel, and also on the height of the tire. I am running a 255/70/R15 on the back of my 72. They look awesome from any angle, but, the pass. side one rubs if you hit a bump just right.

 

Heres a chart http://www.dodgestang.com/Tire%20Fit...de%2069-70.pdf

 

Should be able to fit a 315 at least. That's what we have in a 67, and a 70 in a smidgin' bigger.

 

i saw 335's on a 65 last week seemed fine to me

 

I think a 275is the biggest you can go with room to move..and no rubbing at stock height

 

A lot of will it fit is your ride height lower the car more likely a big tire will rub.

 

The largest tire I have seen installed on the rear of a 69 without major modification was 295/35/18. No mods to the axle, but a BFH was needed to clearance a couple of areas in the wheel well. Here's the thread:

http://www.1969stang.com/mustang/for...ead.php?t=2301

This guy has some sweeeeeeeet cars!!!

 

Your leaf springs and tire diameter are going to be the biggest factor. I have MT 26x10.5 on mine with no problem but if your leaf springs sag or you run a taller tire, you are going to have issues. I think, anything much about 10.5 wide is going to be dependent on you specific car.