Bridge Laws - Where to set trailer tandems? How do you figure it out?

Under 30k I just leave 7 holes from the front. Over 30 I slide tandems based on weight and I try not to haul over 42

 

The standard king pin is set 3' back from the front edge of the trailer. For a 53' trailer, that leaves 50' behind the king pin. Depending on what state you are working in or through, is how you set the distance for axle to king pin. [check in a truckers atlas for each state requirements] Example; for CA, 40' from king pin to center of rear axle, measure 10' from the rear most point on the trailer, this spot will be where the maximum length the tandems can be back. Anything in front of that 40' spot is OK.

Pups and some container chasis do not follow this 3' rule on king pin placement.

 

Most bridge laws are anywhere from 41 thru 45 feet. This is measured from the centerline of the king pin to the center line of the front axel on the trailer. The standard Rand McNally truck map book has bridge laws for all states including those for spread tandems, doubles, triples and b-trains. Most state scale houses have a length gauge when you roll across the scales. Most states are starting to pay more attention to trailer length especially in larger cities.

 

The center of the last axle

 

Some states are to the center of the axle group.

 

States are different on which place the measurement concerns; i.e. CA center of rear axle. As was stated, center of axle group and some can be center of forward.

Check the truckers atlas it has the measure and place for each state.

 

I set mine to the 41' center of the tandems as default. Unless it's loaded backasswards that usually works. Legal pretty much everywhere except California and provides the best compromise between maneuverability and backing ease. The farther the tandems are back the easier it is to control your tailswing when backing into a spot. Of course that goes out the window at truckstops like the Love's in Tacoma....