Understanding Vehicle Weights and Tow Capacity

All of this information comes directly from our commercial insurance provider with decades of experience in the industry. This information is from the Trailer Renter User's Guide provided by MBA Insurance.

Gross Vehicle Weight Rating (GVWR): is the maximum permissible weight of the

vehicle when fully loaded for travel. The tow vehicle and the trailer each have GVWR.

Unloaded Vehicle Weight or Dry Weight (UVW): the actual weight of the trailer or

truck as built at the factory. The UVW does not include passengers, cargo, fresh water,

LP gas, or after market accessories.

Cargo Carrying Capacity (CCC): is the maximum permissible weight of personal

belongings that can be added. CCC is equal or less than GVWR minus UVW, full fresh

water weight and full LP gas weight.

Gross Axle Weight Rating (GAWR): is the maximum allowable weight that an axle is

designed to support. The tow vehicle and trailer each have GAWR.

Gross Combined Weight Rating (GCWR): the maximum permissible weight of the

tow vehicle and trailer combined when both are fully loaded for travel.

Gross Vehicle Weight or Trailer Weight (GVW), (GTW): this is not a rating; this is the

actual weight of the tow vehicle or trailer when they are fully loaded for travel.

Tongue Weight: is the amount of weight pressing down on the vehicle’s hitch from the

coupler of the trailer when the trailer is fully loaded for travel.

MATCHING TOW VEHICLE TO THE RIGHT TRAILER

A manufacturer determines a tow rating based on the vehicle when it is empty. It does

not include the cargo, passengers, after market accessories or any additional weight

placed in the vehicle. Any weight added to the tow vehicle reduces the tow rating by

that amount.

For Example: Tow Rating of Vehicle: 7,900 lbs

Cargo in the Tow Vehicle: 200 lbs

Passengers & Driver 500 lbs

Additional 50 gal. Fuel Tank: 305 lbs

Actual Tow Rating: 6,895 lbs Tow Vehicle

TRAILER

UVW in the Brochure 5,730 lbs

Dealer Ordered Options 370 lbs

Dealer Installed Options 100 lbs

Cargo in the Trailer 300 lbs

Water 8.3 X 32 gallons 266 lbs

LP gas 4.23 X 14 gallons 59 lbs

Gross Trailer Weight: 6,825 lbs

Tow Rating 6,895 lbs

Minus GTW 6,825 lbs

Equals 70 lbs before tow rating is exceeded.

There is another important weight rating that comes into play that is the Gross

Combined Weight Rating (GCWR). This is the maximum allowable combined weight of

the tow vehicle and the trailer when both are fully loaded for travel.

You should never tow a trailer that is pushing the limit on the manufacturers tow rating

or a combined weight that is pushing the tow vehicle GCWR. Pushing the weights over

the limits allowed put the driver and passengers in a dangerous situation for them and

surrounding traffic. 

Remember to include all factors in your weight calculations:

1. Add the UVW of the trailer, make sure that it includes all options.

2. Add the weight of any aftermarket accessories like a battery or a satellite

dish.

3. Add the weight of any cargo you put in the trailer.

4. Add the weight of water and LP gas that will be on the trailer. Water

weighs 8.3 pounds per gallon. LP gas weighs 2.4 pounds per gallon.

5. Add all weight of passengers in the tow vehicle.

6. Add the weight of any cargo in the tow vehicle.

7. Add the weight of any after market equipment added to the vehicle.

There are two methods to ensure you do not put yourself or others in danger when

towing. A simple method to use, that will add a built in safety margin, is to take the

GCWR of the tow vehicle minus the GVW, the actual weight of the fully loaded tow

vehicle, and this equals the maximum GVWR of a trailer that you can consider

purchasing or renting for towing.

For Example:

GCWR – GVW = Maximum GVWR of the Trailer

GCWR of our Tow Vehicle 14,000 lbs

Minus GVW of Tow Vehicle 7,105 lbs

Max. GVWR of Trailer 6,895 lbs

GVWR of the Trailer 6,900 lbs

UVW in the brochure 4,355 lbs

Dealer Ordered Options 370 lbs

Dealer Installed Options 100 lbs

Cargo Loaded in Trailer 300 lbs

Water 8.3 X 32 gallons 266 lbs

LP gas 4.23 X 14 gallons 59 lbs

Gross Trailer Weight 5,450 lbs

GCWR 14,000 lbs

GVW + GTW 12,555 lbs

1,445 lbs to spare 

To build a better safety margin you can use the 75% rule. The 75% rule ensures a built

in margin of safety and is a good rule to follow if you plan to tow in higher elevations. At

10,000 feet above sea level you would need to reduce vehicle ratings by 20% to

maintain performance. Before you can apply the 75% rule you need to reduce your

ratings to see how you can safely tow at 10,000 feet above sea level.

For Example:

Tow Vehicle GCWR X 80% to get a 20% reduction 14,000 lbs

X 80%

11,200 lbs

Tow Vehicle GVWR X 80% to get a 20% reduction 8,800 lbs

X 80%

7,040 lbs

11,200 lbs minus 7,040 lbs = a maximum tow rating of 4,160 lbs at 10,000 feet

above sea level.

The 75% rate will calculate the most weight we should tow to still maintain performance.

Tow Vehicle GCWR 75% 14,000 lbs

X 75%

10,500 lbs

Tow Vehicle GVWR 75% 8,800 lbs

X 75%

6,600 lbs

10,500 lbs minus 6,600 lbs = maximum tow rating of 3,900 lbs at 10,000 feet above

sea level.

By applying the 75% rule and keeping our trailer weight at below 3,900 lbs, we can keep

the tow rating below the maximum 4,160 lbs required to maintain vehicle performance.

By applying the methods above combined with the proper match between your tow

vehicle and trailer. However, the way to get true and accurate weights is to the weigh

both the tow vehicle and the trailer fully loaded for travel.