Recovery/tow trucks weight regulations

Believe me I know too. Try getting an oversize permit to go across the U.S.. It just can not be done. But I have a question that I have been thinking about. When you load up a tractor by the front does the shift in weight back onto the rear axles of the tow truck in up less that overload because you're mostly taking the steer axle weight?

 

Most heavy wreckers are running heavy on their steer axle when not towing so they have weigt to "lose" when it is transferred to their drive axle as they lift the disabled truck. This can result in a tow truck overloading their drive axle group, which is why they usually have axle weight exemptions for first moves from the side of a highway. The same leverage forces at work to shift steer weight to the rear on the tow truck work to a much lesser extent on the vehicle in tow but some weight does transfer back to the wheels on the ground. Usually the transfer is not enough to overload the towed vehicle's axle group, but it does happen, especially wih heavy straight trucks being towed from the rear. The tow truck can control their axle overload by moving the towing attachment closer to the tailboard of the wrecker, the less overhang past the tail the less lever action to transfer weight so more stays on their steer axle, which is why old tow trucks that used truck bars to tow from the bumper could be so much shorter in wheel base, modern trucks have to be as long as they are due to the type of tow attachments we use today.

When we lift a 12,000 pound steer axle on a typical toad tractor we add about 15-18,000 pounds to our drives, not much except the average heavy duty wrecker, not the big rotators but just a 35 or 50 ton capacity tow truck, weights in empty at about 50,000 with 15-20k on the steers due to a heavy front counterweight and about 30k on the drives, so there isn't a lot of riom for transfer before going over statutory weight limits in most states.