What You Need to Know About Sliding the Fifth Wheel. 230 Pounds or 500?

Excess distance between the tractor and the trailer means unnecessary fuel losses on the road. The greater the distance, the higher the aerodynamic drag.

Many drivers don't really understand how sliding the fifth wheel affects axle weights, because for years brochures have repeated the old number: "500 pounds." That information is outdated and does not reflect how modern trucks are built.

In the past, the fifth-wheel slide increment was 4 inches. Today, it is typically only 2 inches.

The math is simple and very accurate. To calculate how much axle weight changes when you slide the fifth wheel:

1. take the total weight being shifted with fifth wheel;
2. divide it by the truck's wheelbase;
3. then multiply that result by the distance you slide the fifth wheel.

In real-world numbers: with a wheelbase of approximately 230 inches and a modern fifth-wheel slide increment of 2 inches, moving the fifth wheel by one position changes axle weight by about 230 pounds, assuming you are already close to the limits of 12,000 lbs on the steer axle and 34,000 lbs on the drive axles.

Now you know what to expect from axle weights when you move the fifth wheel. This information is built into Mouse Scale Light, so there's no more guesswork.

One More Tip

If possible, don't slide the fifth wheel at a truck stop. It's better to set it in the correct position at your home terminal, bobtail, together with a mechanic you trust.

It only takes a few minutes, makes life easier, and reduces the risk of problems on the road.