2013 Toyota Tundra Regular Cab Owners Manual - Page 241
2013 Toyota Tundra Regular Cab Manual
Page 241 highlights
2-5. Driving information GCWR, TWR, Unbraked TWR, Fifth wheel and Gooseneck towing TWR Confirm that the gross trailer weight, gross combination weight, gross vehicle weight, gross axle weight and tongue weight are all within the limits.