How far forward can you move your tandems?

Most of the time, drivers have problems moving their tandems backwards, to take weight off of their trailer tandems. But there are a couple of situations where drivers need to be careful of how far forward they move their tandems.

Issue number 1

The first issue is bridge laws, at a certain distance you will not be able to load as much weight onto your vehicle. When the distance between the first axle of your tandems is 35 feet from the rear axle on your tandems to the last axle of your trailer tandems, you will have to reduce the amount of weight that you load onto your truck.

Here is the part of the bridge table that shows this:
Bridge Table Watch out for 35 foot mark

This means when axles 2 and 5 are 35’ apart (see picture below), you can only have about 32,750 lbs on your tractor tandems and your trailer tandems.
To avoid having this weight reduction, keep the distance between axles 2 and 5 at least 36 feet apart.

Semi Truck Figure Watch out for 35 foot mark

Issue number 2

Some jurisdictions restrict your truck to have a rear overhang that is “35% of the trailer wheelbase.” In these states you cannot have a short distance between your kingpin to your tandems, and then a long distance from your tandems to the end of your trailer. If you operate a typical 53’ van trailer, that has 3’ kingpin setback, then you cannot have the center of your tandem axles less than 37’1” from the kingpin.
Where does this apply?

  • Canada
  • Maine
  • Maryland
  • New Jersey

Semi Truck Figure 37 feet 1 inch for effective overhang

6 thoughts on “How far forward can you move your tandems?”

  1. Yes, except for the two issues that are described in this article. These rules apply on the interstate and in the city (if your state follows bridge laws everywhere).

  2. More of a question. In 29 years of driving I have never moved the trailer tandems forward past the 40′ mark. My current employer told me to move 2 holes past the mark because I was over on my drives. Was this legal ? Hope I don’t sound dumb but never had an issue until now.

  3. Hi Chester, its not a dumb question at all. There are two issues that you can potentially run into by moving your tandems too far forward. #1 is that you will have a reduction in weight on your drive + tandems according to the bridge formula. But this will only start to have an effect when the distance from your first drive axle to your last trailer axle is less than 36′. (So not an issue for you I think). Issue #2 is that in Canada, Maine, Maryland and New Jersey, you can’t be less than about 37’1″ on a standard semi truck due to the ‘effective rear overhang’ rule. More info on both of these issues can be found here: How far forward can you move your tandems?

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