Guidelines for Towing a Trailer

  1. Because a tow vehicle and a trailer form an articulated (hinged) vehicle, weight considerations are very important to safe towing. The tow vehicle must be a proper match for the trailer.
  2. The ball and coupler hitch is used on a wide variety of tow vehicle combinations. This hitch consists simply of a ball attached to the rear of a tow vehicle and a coupler (socket) at the tip of a tongue or A-frame attached to the front of the trailer. This hitch is commonly used on recreational trailers.

    A load-distributing hitch is used for heavier models such as utility trailers, boat trailers and travel trailers. These load-distributing hitches use special equipment to distribute the tongue load to all axles of the tow vehicle and trailer to help stabilize the tow vehicle. Here are some terms you should know when discussing hitch adjustment and in evaluating hitch performance:

    • Receiver: Hitch platform fitted to the tow vehicle.
    • Ball Mount: A removable steel component that fits into the receiver. The ball and spring bars (only on load-distributing hitches) are attached to it.
    • Sway Control: A device designed to lessen the pivoting motion between tow vehicle and trailer when a ball-type hitch is used.
    • Coupler: A ball socket at the front of the trailer A-frame that receives the hitch ball.
    • Spring Bars: Load-leveling bars used to distribute hitch weight among all axles of tow vehicle and trailer in a load distributing, ball-type hitch.
  3. Weight definitions:
    • Base Curb Weight — Weight of the vehicle and trailer not including cargo or any optional equipment.
    • Cargo Weight — Includes cargo, passengers and optional equipment. When towing, trailer tongue weight is also part of the Cargo Weight.
    • Gross Axle Weight (GAW) — The total weight placed on each axle (front and rear). To determine the Gross Axle Weights for your vehicle and trailer combination, take your loaded vehicle and trailer to a scale. With the trailer attached, place the front wheels of the vehicle on the scale to get the front GAW. To get the rear GAW, weigh the towing vehicle with trailer attached, but with just the four wheels of the vehicle on the scale. You get the rear GAW by subtracting the front GAW from that amount. In the absence of a scale, calculate the Front Gross Axle Weight by adding the Front Axle Curb Weight to the Cargo Weight (including passengers) assigned to the front half of the van. Calculate the Rear Gross Axle Weight by adding the Rear Axle Curb Weight to the Cargo Weight (including passengers) assigned to the rear half of the van and the tongue weight of the trailer.
    • Gross Axle Weight Rating (GAWR) — The total weight each axle (front and rear) is capable of carrying. These numbers are shown on the Safety Compliance Certification Label located inside the driver side doorframe. The total load on each axle (GAW) must never exceed its GAWR. 
    • Gross Combination Weight (GCW) — The weight of the loaded vehicle (GVW) plus the weight of the fully loaded trailer. It is the actual weight obtained when the vehicle and trailer are weighed together on a scale. 
    • Gross Combination Weight Rating (GCWR) — The maximum allowable weight of the towing vehicle and the loaded trailer (including all cargo) that the powertrain can handle without risking costly damage. The measured GCW must never exceed the GCWR. (Important: The towing vehicle's brake system is rated for safe operation at the GVWR — not GCWR. Separate functional brake systems should be used for safe control of towed vehicles and for trailers weighing more than 3,000 lbs. when loaded.)
    • Gross Vehicle Weight (GVW) — Base Curb Weight plus actual Cargo Weight. It is the actual weight that is obtained when the fully loaded vehicle is driven onto a scale.
    • Gross Vehicle Weight Rating (GVWR) — The maximum allowable weight of the fully loaded vehicle (Base Curb Weight plus options plus cargo). The vehicle's measured GVW must never exceed the GVWR. The GVWR, along with other maximum safe vehicle weights, as well as tire, rim size and inflation pressure are shown on the vehicle's Safety Compliance Certification Label.
    • Gross Trailer Weight — Is the highest possible weight of a fully loaded trailer the vehicle can tow. It assumes a towing vehicle with mandatory options, no cargo and the driver only (150 lbs.). The weight of additional optional equipment, cargo and hitch must be deducted from this weight.
    • Payload — Maximum allowable weight of cargo that the vehicle is designed to carry. It is Gross Vehicle Weight Rating minus the Base Curb Weight.
  4. Safety:
    • Perform a safety inspection before each trip: Make sure that the pin securing the ball mount to the receiver is intact, the hitch coupler is secured, spring bar hinges are tight with the safety clips in place (load equalizer or weight distributing hitches), safety chains are properly attached, and the electrical plug is properly installed.
    • Practice trailer backing: Backing a trailer into tight places is easier than it looks, but it does take some practice. It's best to practice in a parking lot and in a vehicle that allows you to see the trailer through the rear window. Vans, trucks and campers that have obstructed rear views require more practice and the use of side mirrors. In either case, be patient and make steering adjustments slowly and a little at a time.
    • Watch your tongue weight: How a trailer handles down the road depends upon tongue weight. Too much weight will cause the rear of the trailer to sway and make the tow vehicle difficult to control. The tongue weight should not exceed 200 pounds for trailers up to 2,000 pounds. Tongue weight for trailers over 2,000 pounds should be 10-15 percent of the trailer's loaded weight. 
    • Take care of tires: It's wise to periodically check tires for wear, cuts or other damage and replace as needed. Above all, maintain the tire pressure recommended by the manufacturer, located on the tire sidewall. Improperly inflated tires will cause them to wear out quicker and reduce fuel mileage. 
    • Keep bearings greased: Wheel bearings are the heart of trailers. They need to remain airtight and packed with fresh grease. Poorly greased bearings will overheat and deteriorate, creating serious problems if they fail. They should be inspected and repacked at least once a year, depending upon the amount of use. Lay your hand on your wheel hubs after traveling. If they feel unusually warm, you may have a problem. But why wait? Routine maintenance is good prevention.       
    • Go wide on turns: Be careful making sharp turns or sudden moves when trailering. The trailer tends to cut corners more sharply than the tow vehicle, which can be dangerous when cutting corners close to curbs, other vehicles and roadside obstructions. Striking solid objects at an angle can cause tire damage, and more importantly, cause you to lose control momentarily.
    • Be a weight watcher: When loading, balance the cargo with 60 percent of the weight near the front.
    • Secure the trailer: Keep the safety chains provided on most trailers fastened securely to the tow vehicle in case the hitch fails. Cross the chains under the trailer tongue and allow slack for turning. For additional security, padlock the trailer hitch to the tow vehicle. That will also prevent someone from stealing the trailer while you're away from the vehicle. 
    • Keep the lights working: The trailer's electrical components are subjected to a great deal of adverse conditions, so check them periodically. Ask someone to step behind the trailer to make sure the taillights, brake lights and turn signals are working properly. If signals are dim, perhaps there is a bad connection or you need a more powerful flasher unit on the tow vehicle. An occasional shot of WD-40 into the pigtail wiring connector will reduce corrosion.
    • Make sure your vehicle has towing power: Just because a vehicle has the power to pull a loaded trailer down the road doesn't mean it has the guts to haul it up steep hills, or that brakes are capable of holding it on a steep incline. Follow manufacturers' towing guidelines and never exceed tow limits. Too much trailer weight can cause an accident, or pull the tow vehicle down a steep incline.  

Purdue University, 610 Purdue Mall, West Lafayette, IN 47907, (765) 494-4600

© 2015 Purdue University | An equal access/equal opportunity university | Copyright Complaints | Maintained by Transportation Service

Trouble with this page? Disability-related accessibility issue? Please contact Transportation Service at