What Is Tongue Weight? (The Number That Controls Trailer Sway)

Quick Answer: What is tongue weight? Tongue weight is the downward force the trailer exerts on the hitch ball of your tow vehicle. It should be 10–15% of the total loaded trailer weight. Too little tongue weight causes trailer sway. Too much overloads your rear axle. Getting it right is one of the most important things you can do for safe towing.

Once you know your tongue weight, plug it into our free towing capacity calculator to see how much payload you have left.

Tongue Weight Definition

Tongue weight (also called hitch weight) is the static downward force applied to the hitch ball of your tow vehicle by the trailer coupler. It is measured in pounds and is a direct result of how the trailer is loaded. The tongue weight transfers to your vehicle’s rear axle and counts against your truck’s payload capacity.

The 10–15% Rule

For conventional trailers with a ball-and-coupler hitch, tongue weight should fall between 10% and 15% of the total loaded trailer weight (GVWR).

• 5,000 lb trailer → 500–750 lb tongue weight
• 7,000 lb trailer → 700–1,050 lb tongue weight
• 10,000 lb trailer → 1,000–1,500 lb tongue weight

This range is not arbitrary. It is the result of decades of towing experience and engineering research. Stay in this range and your trailer will track behind your truck predictably. Stray outside it and problems multiply quickly.

What Happens With Too Little Tongue Weight

When tongue weight falls below 10%, the trailer becomes rear-heavy. The trailer’s rear end wants to swing out — triggering trailer sway. Sway at highway speeds can be violent and uncontrollable. This is the most common cause of trailer accidents among newer towers.

Signs of too little tongue weight:

• Trailer sways or fishtails at speed
• Rear of tow vehicle lifts slightly — front feels light
• Trailer feels unstable in crosswinds or when passed by large trucks

What Happens With Too Much Tongue Weight

When tongue weight exceeds 15% (or exceeds your hitch’s tongue weight rating), it overloads your rear axle. The rear of the truck squats, the front lifts, and steering becomes dangerously light. Too much tongue weight also pushes you over payload capacity and GVWR.

Signs of too much tongue weight:

• Rear of truck squats noticeably with trailer attached
• Headlights point upward
• Steering feels vague or light
• Front tires wear unevenly

How to Measure Tongue Weight

There are several ways to measure tongue weight:

• Tongue weight scale ($30–$80) — place it on the ground under the coupler, jack the tongue down onto it, read the number
• Truck scale / CAT scale — weigh the truck fully loaded with trailer attached, then unhook and weigh the truck alone; the difference in rear axle weight is roughly the tongue weight
• Bathroom scale method — works for lighter trailers only (under 300 lb tongue weight)

How Tongue Weight Is Affected by Loading

Tongue weight is entirely a function of how you load your trailer. Heavy items loaded in front of the trailer axle add to tongue weight. Heavy items behind the axle reduce tongue weight and can push it dangerously low.

The rule of thumb: 60% of cargo weight should be in the front half of the trailer (ahead of the axle). This naturally produces the right tongue weight range and keeps the trailer stable.

Tongue Weight Ratings to Know

• Hitch tongue weight rating — your hitch receiver has a separate tongue weight rating (often 10–15% of its max towing capacity). Never exceed it.
• Ball mount tongue weight rating — the drop or rise ball mount also has its own rating
• Vehicle rear axle rating (RAWR) — limits how much weight can press down on the rear axle, factoring in tongue weight and cargo

Weight Distribution Hitches and Tongue Weight

For heavier trailers where tongue weight would otherwise overload the rear axle, a weight distribution hitch redistributes the tongue weight across all four wheels of the tow vehicle (and sometimes the trailer axles too). This allows you to safely tow heavier trailers while maintaining proper handling. Most weight distribution hitches are required when tongue weight exceeds 750–1,000 lbs.

Related Towing Terms

• What Is GVWR?
• What Is Payload Capacity?
• Trailer Sway Control Guide
• Weight Distribution Hitch Setup
• Complete Towing Safety Guide