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How Overweight Loads Work

How to Tow an Overweight Load
Each of these two wheels is connected to two others on the opposite side by an axle.
Each of these two wheels is connected to two others on the opposite side by an axle.
marekp | ©istock photo

State and local governments regulate overweight loads for one reason -- to preserve their infrastructures. Repeatedly driving overweight loads on highways, local roads and bridges wears them down over time, resulting in ruts, cracks and potholes. A government study found that a single overweight truck carrying the maximum 80,000-pound (36,287-kilogram) load does as much damage to a highway as 9,600 cars do[source: USA Today].

One of the big problems with heavy loads is that extra weight has an exponential effect on the road's surface. Let's say you have two trucks, each with an overweight load. One comes in at the legal limit of 20,000 pounds (9,071 kilograms) and the other at double that amount -- 40,000 pounds (18,143 kilograms). Instead of doing twice as much damage, the overweight load actually comes in at 16 times more damage.

If you're planning on towing an overweight load, here are some things to consider: Loads are typically broken down into two groups -- axle load and tire load. The axle is the central, rotating metal shaft that connects the wheels opposite each other. Axle load refers to the total weight spread out over the entire vehicle. Tire load references the narrow concentration of weight from the load sitting on each tire. Axle weight isn't affected by the width of a tire, so 20,000 pounds (9,071 kilograms) sitting on a 12-inch (30-centimeter) wide tire puts the same stress on a road or bridge as that same weight on narrow, 6-inch (15.24-centimeter) tires. Permitting is typically broken down into categories depending on how many axles and tires you have compared to how much weight you're hauling.

Towing overweight loads requires some experience in order to make it safe journey. Stopping distance and how your car or truck handles are the two main issues at play. Auto brakes respond differently when there's extra weight involved -- the same goes for steering. You'll want to give yourself extra space between you and the car in front of you and anticipate your stops well in advance. Sudden swerving is difficult to control with an overweight load as well, so the straighter and less congested your route, the better.

Now that you know a bit about how to tow an overweight load, head to the next page for some more tips on the process.