So can I fit 35x12.50x16.5 on to a 84 f250 6.9 stock no lift?

 

I had 33 12.50 16.5s on a 97 f250 and I was rubbing the bumpers. another thing from the 265 75 16's they crushed my fuel mileage.

 

You can, but things will rub. I bought a 1983 bronco with 35's and no lift. They chewed the tops of the fenders as well as the front and the suspension. You would be better off if you at least had a leveling kit or you can do some fender trimming.