Towing Capacity 80% Rule Calculator

Many RVers keep the loaded trailer at or below 80% of the truck's max tow rating, leaving margin for wind, hills and heat.

Is 80% a law?

No. It's a rule of thumb, not a legal limit. The hard limits are the manufacturer ratings, and payload often runs out before 80% of tow rating does. Check both.

Safety note: These are planning estimates, not a guarantee your setup is safe or legal. Always verify with your truck's door-jamb sticker, the manufacturer's towing guide for your exact configuration, the trailer's VIN sticker, and a real weigh at a CAT scale. Never exceed any rating.

Last reviewed October 2026 by Jim Frith.