09/16/2026
"Should I go Load Range F before I tow with my F-250?" We get this one constantly, and the answer surprises people.
Federal law already settled it. FMVSS No. 120 requires that the tires on an axle add up to at least that axle's weight rating. Your factory Load Range E tires were selected to clear your rear axle before the truck left the line. They are not a weak link somebody forgot to fix.
So Load Range F raises a ceiling you are already not permitted to reach. Towing capacity is GCWR. Axle capacity is GAWR. Neither one has a tire term you can edit.
The mistake that actually costs people capacity runs the other direction: upsizing into a size with a lower load index. LT275/70R18 at load index 125 gives you 7,276 lb across the rear axle. Drop to LT285/75R17 at 121 and you are at 6,394 lb, having given away 882 lb without meaning to.
Full breakdown of all five ratings and which one really limits your truck:
https://www.performanceplustire.com/Blog/load-range-f-tires-three-quarter-ton