Some time ago, a Compliance and Logistics Coordinator for a shipper in California asked the following question to Big Truck Guide:

Is it prudent to ask a carrier on California to have rear tandem wheels set in the most rearward position throughout the shipment?

In regards to your question, I will address whether it is legal, and if it is safe:

Is it legal to operate a trailer with the tandems all the way back, in California?

  • On ‘STAA Routes’ – Interstates and some state roads (blue roads on California maps):
    • Yes – Trailers 48’ or shorter
    • No – Trailers 48’ to 53’ must comply with a Kingpin to Rear Axle distance of 40’.
  • On ‘California Black Routes’ – California designated truck routes:
    • No – All trailers, regardless of length, must comply with a Kingpin to Rear Axle distance of 40’

Is it safe to ask a carrier to operate with the rear tandems all the way at the rear of the trailer?

  • No. The kingpin to rear axle distance regulations are put into place to maintain road
    safety. On windy roads, the trailer will track further away from the truck and can cross into other lanes. In urban areas, the truck will have a harder time turning and can more easily damage curbs and/or people standing on sidewalks.

Although many shippers prefer to load trailers with the rear axles all the way back to increase safety at the dock/trailer interface, it is required by law in many states to move the axles forward, and it is safer to operate in this way when traveling down the road.
Maps of these routes can be found through the California legal documentation here: California Truck Guide