I don't think I have seen many truckers traveling in California under
70mph unless in city or up mountain grades.  I just came back from
California traveling I-15 between San Diego and Riverside then I-10 to
Phoenix.  I drive those and other California highways many times each
year.  Truckers traveling 55-60mph is rare.

The tow vehicle, trailer, hitch etc. have a lot to do with it.  If there
is fishtailing going on then somethings wrong and speed is most likely
not the cause but certainly the two don't mix.

Everyone has their own opinion as to whats unsafe.  Some people view
driving at 75mph to be unsafe.  In Arizona the speed limit was lowered
from 65mph to 55mph whether towing or not.  It is now 75mph while
California is 70mph unless in city or mountainous regions etc.

Whats unsafe is the attitude of many California drivers.  Need to change
lanes?  Forget about using your turn signal.  That just tells the person
behind in the next lane to speed up and close you out.  California has
some of the fastest drivers I have seen anywhere.  Last week on I-15,
I-10 and highway 91 70mph would be among the slower drivers easily.

I tend to tow at 65-70mph if on flat ground with little traffic and no
wind.  It really depends on road, traffic conditions as well as what I'm
towing and what I'm towing with.

Just completed a trip from one end of California to the other in a 32' class
A towing a Jeep Cherokee.  I was running 60 -62 mph on the interstates.
18-wheelers, and just about everyone else for that matter, were blowing by
me.

Riverside to Las Vegas was even better.  Trucks had to be doing at least 75
mph.

I towed at 85 on I-40 and I-30 Sunday. Yanking a 14000 pound 5th wheeler
behind me with my Dodge 2005 Ram 3500 Heavy Duty Dually 600 series truck.
(BART-Big Assed Red Truck).  I even had the over drive on and cruise
control.  I still got run off the road by the 18 wheelers heading to Dallas.

With all due respect, I cannot imagine towing a fishtailing trailer and any
speed, especially 75 MPH, without knowing it.  Safe speed depends on the way
the trailer and tow vehicle are set up, driver skill and road conditions (to
mention a few factors).  I do, however agree that pulling nearly any TT at
75 is over the edge.

Might not be so agreeable about 65 MPH with a well balanced 5th wheel and
tow vehicle.

RonB

Living on the NW edge of California, one of the drawbacks is that
whenever I want to go someplace to the southeast I have to traverse
900 miles at crummy artificially-low speeds until I can get out of the
state.

I disagree with those who claim that truckers typically travel 70 on
I-5. I set my speed at 62 or 63, and it is an accurate speed
(calibrated digital speedometer checked many times via both radar and
timed distance). I pass some trucks, and a smaller number pass me, but
they are only rarely doing more than a mile or two faster than I am.

I do recognize that, on I-10 and I-40 as you approach Arizona the
speeds do tend to increase, and then of course when you cross the
border they move up to the normal traffic level of 70-75.

I also disagree completely that the split speeds in California are
safer, and I would be happy to look at objective or empirical evidence
that they are. I would offer that any time some segment of traffic is
required to go slower than another segment it is always more hazardous
than it needs to be.

Part of the craziness is that both a non-towing 50,000 lb Prevost and
a Greyhound bus can go the full car speed limit. Tack a 3500-lb car on
the back and you have to drop the speed.

The California rules have recently been clarified in two ways. It has
been noted before that the old "Trucks/Autos with Trailers" signs have
been modified to say that they apply to any vehicle towing anything. I
haven't seen anybody posting the other change, which says that trucks
with more than 2 axles have to go 55. That means a 2-axle bobtail has
also been exempted from the rule.