Why 40’ kingpin length in Ca?

My assumption is for off-track concerns. There are some skinny roads, tight off/on ramps, etc.

 

Holdover from the days of 45' and 48' trailers.

 

48s are exempt from the 40' KPRA rule aren't they?

 

There are 48' california spreads so I imagine not.

 

There are a number of things that go into that regulation. Basically it is a combination of weight distribution and bridge laws. They claim it puts less wear and tear on the roads.

 

Yes, they have been for a few years but they didn’t used to be.

 

It’s not a bridge law, bridge laws deal with weight. If that were the case they’d want to increase the distance between axle groups not decrease it. It’s maneuverability, same reason you still see so many truck-trailers and short doubles running out there.