Towing Capacity Checker

Towing safely is not a single number. A setup can sit well under the advertised tow rating and still be illegal or unsafe because a different limit is already maxed out. This tool checks five limits at once and shows how much of each one you are using.

The weights

• Curb weight: the tow vehicle empty, with fluids and a full tank, but no people or cargo.
• GVWR (gross vehicle weight rating): the most the loaded tow vehicle may weigh on its own wheels. Your payload capacity is simply GVWR minus curb weight.
• GCWR (gross combined weight rating): the most the vehicle and trailer may weigh together.
• Tongue weight: the download the trailer places on the hitch. It is part of the trailer's weight, but it rides on the tow vehicle, so it counts against payload.

The five checks

1. Tow rating — loaded trailer weight ≤ max towing capacity.

2. Trailer GVWR — trailer weight plus its cargo ≤ the trailer's own rating.

3. Tongue weight ratio — tongue weight as a share of loaded trailer weight. Conventional hitches want 10–15%; fifth wheels and goosenecks want 15–25%. Too little causes trailer sway, too much overloads the rear axle and lightens the steering.

4. Vehicle GVWR — curb weight + passengers + cargo + tongue weight ≤ GVWR. This is the limit that catches most people out; tongue weight alone can eat half a truck's payload.

5. GCWR — curb weight + passengers + cargo + loaded trailer ≤ GCWR.

Reading the gauge

The gauge shows the binding constraint: whichever limit you are using the largest share of. That is the one that will stop you first, so it is the number worth watching. Under 75% is comfortable, 75–90% is worth noting, 90–100% leaves no margin for a heavy passenger or a full water tank, and anything past 100% is over the limit.

Tongue weight is the exception. It has a target window rather than a ceiling, so it reports your actual share of trailer weight — the number you compare against 10–15% — and it never drives the gauge. Sitting at the top of the window is fine, not "full", and being under 10% is a problem in its own right rather than spare capacity.