It went by GVWR as well.

Here is a simple chart, and is the general rule...

1980-1983: F-100: GVWR: 4700/5000: with Power Brakes: 10inch brakes: 5x4.5

1980-1983: F-100: GVWR: 5150 and 4700/5000 with manual brakes.: 11 inch brakes: 5x5.5

1980-1986: F-150 and U-150: 11 inch brakes: 5x5.5

Source: Ford light truck service specs manual: FPS-365-322-81

 

Hey doug1222556,While I'm thinking of it on 1980-1986 F100/F150 Wheel Bolt Pattern,Question:What is the Diameter of the Wheel Studs on the 1980-1986 F100/F150 PickUps

 

They are 1/2". I had a guy try and tell me he had 5x5 1/4" Ford wheels one time. Let me re-phrase that he strongly insisted! (That's what you get if you measure the 5x5 1/2" pattern center to center).

 

Doug, thanks for clarification. I been reading about my rims being 5.5 and sure as shiznit...if you measure it is 5.25. Started to worry. Why the hell it measures one length and standardizes to another is crazy.

 

What type of truck do you have? Tell us the model and info and we can tell you what size you need.