In response to dittle's post about the weight of his truck, back in June of 2001, my dad ordered a new Ford F350 crewcab, diesel, 6 spd manual, extended wheel base dually with a 9 ft service body. The service body only comes up to the height of the rear window. This truck weighed in at the truck scales with a full 40 gallon tank and nothing else in it at 10,000 lbs. dead even. This was back in California and was required in order for it to be registered as it was originally a cab and chassis. Any heavier and would have been registered as a class B truck as it is used as a commercial vehicle.
I have never had any problems withit on a concrete driveway, but have on occasion left black marks. But as everyone else has said, it all depends on the quality of the surface and what it was designed to carry if you will sink. You can always switch over to dualled 11x20s or super-singles if you are really worried about sinking in, but you will still leave some black marks on occasion.
Tobiah