The Stovebolt Site Forums The Parking Lot Big Bolts Reason for Listing Tire Size on Doors?

I just bought a 1960 LCF 60 that still has the original painted lettering on the doors. In addition to the owner's business name and the truck weight, the tire size (8.25-20) was painted on the doors. Anyone know why that would have been done? The truck was used in northwest Ohio both for farm use and in a farm implement dealership. Occasional trips were probably made to Racine Wisconsin to pick up machinery from the factory. Were some tolls at that time based on tire size? I am trying to find out why the tire size was listed.

Thanks for any help.