I have a 69 mustang,and Iwant to know is, what is the biggest rim and tire I can put in the back without doing any mod's to the body!! thanks!

 

check the faq at the top i beileve dodgestangs list has some 69-70 combos listed

 

Yeah, other than the V8 swap thing, that is the next most asked question.
So, because all sections of the MF have this question asked constantly, we have solicited the pros to answer the wheel and tire fitment questions. Ask these guys.
https://mustangforums.com/announcement.asp?id=39