Check a truck and trailer against GVWR, payload, GCWR and the tow rating
Updated October 2026
GVWR (gross vehicle weight rating, on the driver’s door jamb) is the most the loaded truck may weigh. Payload is GVWR minus curb weight, and it must cover passengers, cargo and the trailer’s tongue weight. GCWR (gross combined weight rating, in the owner’s manual or the maker’s towing guide) is the most the truck and loaded trailer may weigh together. The tow rating is the heaviest trailer the manufacturer approves for that exact cab, bed, engine, axle ratio and hitch. Exceeding any one of them is unsafe even if the others look fine.
Curb weight is best measured: run the truck, fueled and empty, across a certified truck scale, then weigh again with everyone aboard and the trailer hitched. Enter the loaded trailer weight (with water, gear and propane), not the dry weight from the brochure.
Take a truck with a 7,000 lb GVWR, 5,000 lb curb weight, 15,000 lb GCWR and 9,000 lb tow rating. Payload is 7,000 − 5,000 = 2,000 lb. A 7,000 lb trailer at 12% tongue weight puts 840 lb on the hitch; with 600 lb of people and gear, 2,000 − 600 − 840 = 560 lb of payload is left. Combined weight is 5,000 + 600 + 7,000 = 12,600 lb, 2,400 lb under the GCWR, and the trailer is 78% of the tow rating. The heaviest trailer this load allows is the smallest of three limits: the tow rating (9,000 lb), the GCWR (15,000 − 5,000 − 600 = 9,400 lb) and payload (1,400 ÷ 0.12 = 11,667 lb), so 9,000 lb.
The same truck (7,000 lb GVWR, 5,000 lb curb, 15,000 lb GCWR, 9,000 lb tow rating) with different trailers and loads:
| Setup | Tongue weight | Payload left | vs GCWR | Share of tow rating | Result |
|---|---|---|---|---|---|
| 5,000 lb travel trailer, 2 adults | 600 lb | 800 lb | 4,400 lb under | 56% | Within limits |
| 7,000 lb travel trailer, 2 adults | 840 lb | 560 lb | 2,400 lb under | 78% | Within limits |
| 7,000 lb travel trailer, family of 4 plus gear | 840 lb | 260 lb | 2,100 lb under | 78% | Within limits |
| 8,500 lb travel trailer, 2 adults | 1,020 lb | 380 lb | 900 lb under | 94% | Within limits |
| 9,000 lb fifth wheel, 2 adults | 1,800 lb | Over by 400 lb | 400 lb under | 100% | Over: payload |
Notice the fifth wheel: well within the tow rating, but its 20% pin weight uses up all the payload. Payload, not the headline tow rating, is the first limit for many trucks.
A conventional ball-hitch trailer should put about 10% to 15% of its loaded weight on the hitch: too little and it can sway, too much and the truck squats and steering lightens. Fifth-wheel and gooseneck trailers put roughly 15% to 25% on the truck. That weight comes out of payload, which is why a family and a heavy camper often exceed payload long before they reach the tow rating.
Most light-duty pickup makers rate towing under SAE J2807, which tests a truck pulling its rated trailer for cooling on a long grade modeled on Arizona’s Davis Dam climb, acceleration on level ground and a 12% grade, combined handling and sway, braking and parking-brake hold, and hitch strength. The rating assumes a driver and one passenger of 150 lb each, popular options installed, up to 70 lb of aftermarket hitch equipment and 10% tongue weight. Heavier occupants, more cargo or a heavier tongue all reduce what you can actually tow.
Ratings assume a properly equipped truck in good condition; heat, grades and wind add strain. BoatUS suggests keeping the loaded trailer to about 85% of the tow rating. Use trailer brakes and a weight-distributing hitch as the manufacturer requires.
Using the trailer’s dry weight. Water (about 8.3 lb per gallon), batteries, propane and gear add hundreds or thousands of pounds. Reading the best-case tow rating for a different cab, axle ratio or engine than yours. Forgetting the hitch and accessories: a weight-distributing hitch, toolbox or bed cover all count as cargo. Exceeding the hitch receiver’s own rating, stamped on the receiver, which can be lower than the truck’s. Ignoring tire load ratings on the truck and trailer. Setting tongue weight too light to save payload, which invites sway.
It does not check axle ratings (GAWR), hitch receiver ratings, tire load capacity, trailer brake requirements or state towing laws, which vary. A truck scale gives real numbers, and a hitch installer or the dealer can confirm the ratings for your exact configuration by VIN.