or how much can my truck tow?
Determine How Much Your 1980 - 86 Ford Truck Can Tow
Ford put the towing capacity info in the owner's manuals, but many of those are missing today. In addition, in the early manuals the tables containing the info were quite long. For instance, in the 1981 manual there are 27 pages of complex tables. But, by 1985 someone at Ford simplified things dramatically - there are only two tables covering the F150's, F250's, and F350's. So, those two tables are what I'm including here. However, by 1985 the F100 was long gone so the tables don't cover them. Given that I'm also including the two pages from the 1981 manual that cover the F100's.
But, before we get to that we need to discuss terminology. The 1985 manual says:
Once these two figures are found, the GCWR minus the Loaded Vehicle Weight determines the Maximum Trailer Weight for your vehicle."
And, if you have the axle code off your door jamb then use the tables on the Axle Ratio page to determine the gear ratio.
Here are the pages from the 1981 owner's manual showing F100 towing capacities:
And here are the two pages from the 1985 owner's manual for the F150, 250, and 350 trucks: