Which way to slide your tandems?

A common task for truck drivers is to slide the tandem axle group along the trailer to adjust the weight on different axle groups.  Knowing which way to move the axles can be confusing.

The tandem axle groups on most trailers can be moved forwards and backwards along the length of the trailer.  Truck drivers want to be able to put the axles where the weight is best distributed, but there are regulations that vary by state and province on how far back the trailer tandems can be moved.  This is called the trailer wheelbase or kingpin to rear axle/tandems distance and refers to the distance between the kingpin on the trailer and the axle group.

What does it matter?

Governments set rules on where to set the tandems to keep the wheelbase of the truck-trailer combination smaller.  The longer the trailer wheelbase, the less maneuverable the truck-trailer combination, and the more curbs the truck will run over.

Truck drivers want to be able to set their wheelbases where ever they want.  If there is a load that is not distributed evenly in the trailer, the truck axles can be overweight, even though the entire truck is not overweight.  In this case, the tandems should be ‘pushed forward’ so more weight would be put on the trailer axles.

Let’s see how this works in practice:

Scenario 1:

TruckandTrailerTandems_SlideForward2

Scenario 2:

Also, it is possible that there is too much weight on the trailer axles.  In this case, the axles can be moved backwards to move weight from the trailer to the truck.

TruckandTrailerTandems_SlideBackward2

Caution! – There are rules governing how far back tandems can be placed.   Click here to see what the laws are where you will be traveling.

 How far should you move the axles?

A good rule of thumb is that one hole on the trailer equals 250 – 300 lbs being moved from the truck to trailer, or vice versa.