new to me! 57,000 original miles. I plan to use it. maybe shoot some paint on the hood only. I think the rest is too original to molest. What would you do?
And the tires are 700x15 8 plys. I'd like to replace them with 6 plys and not loose any height. But my inquiries in town are not very encouraging. What options are out there for tires? It was suggested that 235/75 R15 might be close as to what came out from the factory? But I'm not sure that's what I want. I think I need the aggressive traction tread rears like are on it. I want to use this in the pasture.

 

I'm not a guy who's hung up on being original because quite frankly I couldn't care less as long as the vehicle looks factory or is only tastefully modified looks-wise. So if you're asking what I'd do, I'd paint the thing and help it last. Paint preserves vehicles. It was bad enough that Ford never painted the inside of the sheet metal but now if you're leaving the outside exposed, you're asking for trouble. There's no shame in a repaint and it looks a lot better than this whole "patina" thing everyone is into these days.

The factory tire size was 235/75/15. There are quite a few tires in this size that are available. I haven't checked, but I'm sure you can find a new tire in that size with an aggressive tread to throw on the rear. I wouldn't use the old tires. I haven't seen your specific tires, but they're probably a bit old and sun cracked.

 

I'm with trozei all the way. To me paint looks better then rust or bare metal, but it is all a matter of personal choice. 235/75/15 is what I have on my 92 Flare Side and I drive it all over my old farm with street tread.

 

Nice paint is overrated.

 

This is a P-Metric radial, which was not available until the 1990's. Ford didn't offer any radial tires for F100's until the mid 1970's. Prior years, were only available dealer installed.

The original F100 15" tires were bias ply: 6.70-15 - 7.00-15, 7.10-15 - 7.75-15.

Edit: The above are 1961/66 related. Add 8.15-15 - 8.25-15 & G78-15 (intro'd in 1968) for 1967/72 F100.

 

I think my '70 still has its original bias ply spare tire.. it's a G78-15.

 

I think I found somewhere that the original size may have been 8.25 X 15
With the 700 x 15 the speedometer is reading 5 or 6% low. I think I finally got my fuel line leak fixed. (thought I had it before) so I want to drive a tank or two of gas through it and see how bad the mileage really is. According to the tag it should have 3.50 gears in it coupled to a 4 speed manual.