what size would the stock wheel and tire combo be on a 76 f250 with 7990# on the sticker in the door frame? including backspacing on the rim

 

right now, I have tires that i believe will not maintain my weight rating

 

help? please

 

1967/79 F250 & F350 (SRW) except Camper Specials, 1969/74 E300, 1975/79 E250/350.

Wheel: 16.5 x 6 / Bias ply tire: 8.75 x 16.5
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1967/79 F250/350 Camper Specials.

Wheel: 16.5 x 6.75 / Bias ply tires: 8.75 x 16.5 or 9.50 x 16.5

 

thanks, I appreciate the answer, the next question would involve matching a modern rim (16" or 17") with tire sizes. do you know the size and backspace of this to the 16.5?
ford part # F5TZ1007A