How to Calculate Effective Rear Overhang and Load Overhang in Canada and some States

What is ‘effective rear overhang’ and how does it affect the amount of load overhang you can have on your truck in Canada?
In most Canadian jurisdictions, you are limited to overhang of 35% of the trailer wheelbase. What this means is that the longest amount that you can have from the center of the tandems to the furthest back of the trailer or the load is 35% of the wheelbase. You also have to comply with the overall length of the combination. This rule applies in:

  • Canada
  • Maine
  • Maryland
  • New Jersey

Scenario 1:

So to take a look at the trailer in the picture below:
Effective Rear Overhang Canada 5 Axle Semi Truck

To find out what the effective rear overhang is:

  • 41’ * .35 = 14.35’ effective overhang

This means that in this case with a 53’ trailer, you can have a load overhanging from the end of the trailer up to 4.35 feet (about 4’4”).

Scenario 2:

You have a 53’ trailer, and you want to have that wheelbase as short as possible.
You find that at 37’1”, the trailer is allowed as it is on the road, because this overhang gets smaller and smaller as you shorten the wheelbase.

  • 37’ 1’’ * .35 = 12.9791’ effective overhang
  • 37’ 1’’ = 37.0833 feet
  • 3’ kingpin setback + 37.0833 wheelbase + 12.9791 overhang = 53.0624’ Trailer length

So this means that at less than 37’1” wheelbase, your trailer is no longer allowed to operate because of the overhang. With a trailer wheelbase this short on a 53’ trailer, you are not allowed to have any load overhanging.

Effective Rear Overhang 37' Canada 5 Axle Semi Truck

So, to find out how much you can overhang, you need to take into account how long your wheelbase is, and then adjust your overhang accordingly. It is important to consider how the kingpin setback impacts this distance, and if adjusting your setback is a good idea for your operational considerations. Below is a table that outlines the calculations that you need to do if you have a common combination, a 53′ trailer with 3′ kingpin setback.

Trailer Length Kingpin Setback Trailer Wheelbase Effective Rear Overhang Load Overhang
53′ 3′ 41′ 14′ 4″ 5′ 4″
53′ 3′ 40′ 14′ 0″ 4′ 0″
53′ 3′ 39′ 13′ 8″ 2′ 8″
53′ 3′ 38′ 13′ 4″ 1′ 4″
53′ 3′ 37′ 1” 12′ 11.75″ 0′ 0.8″
53′ 3′ 37′ 12′ 11.4″ Minus 0.6″

2 thoughts on “How to Calculate Effective Rear Overhang and Load Overhang in Canada and some States”

  1. We have a 40 foot gooseneck trailer from the pin is to the middle axle is 37 feet so 35 percent is that is 11 feet just wondered if that’s from the axel or the end of the trailer thanks

  2. 35% of 37′ is 12.95′ (just shy of 13′). This means that the distance from the center of your trailer axle to the end of the trailer can be a maximum of 12.95′.

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