How to Measure a Semi Truck Wheelbase

by Richard Rowe
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Tractor trailers are some of the most modular and versatile vehicles out there; they can come in all shapes, sizes and configurations. That means any particular truck model can come in dozens of different specifications -- wheelbase, among them, possibly being the most important. Then again, it depends on who you ask.


Manufacturers advertise wheelbase according to the distance from the center hub of the steer axle, to the center-point between the two rear wheels on a three-axle truck. So, stick a ruler vertically in the ground right in between the two rear tires, and measure from there to the steer axle. However, possibly more relevantly, officials at the DOT take literally the simplistic technical definition of "wheelbase," which is "the distance between the front steering hub and the rear wheel hub." So, when it comes time to pay tickets for bridge length permit violations, wheelbase measures from the center of the last wheel. Otherwise, advertised wheelbase is from the center of the two wheels, or from the hub of the center axle on a four-axle truck.

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