Anyone know the correct tire size in modern dimensions for a 66 F-100? Mine obviously doesn't have the correct size tires on it.

Thanks

 

The factory tire in 1966 was probably something like an 8.15 x 15 2 ply, 4 ply rating car tire. (or maybe 8.45s) Almost everything in those days was undersize tire wise.

225 70 x 15 or 235 70 x 15 or similar would be a decent substitute. You will also find these in 75 aspect ratios. And in LT load ratings too, methinks.

You can check tire diameter vs. metric size here, 4th calculator down:

Novak Conversions - Gearing & Gearing Math for Jeeps

 

im not sure about the rubber, but the metal was either 15 x 8 or 15 x 10 on a 5 x 5 1/2 bolt circle

 

15x8 or 15x10? In '66? Uhh, no.

15 x 5.5, maybe 15 x 6.

I would go out on a limb here and say Ford never offered a 15x8 or 15x10 on any truck, and probably never on any car either, to this day. (15x7 into the '90s then the diameters went up to 16 & 17 & beyond.