I am a retired log truck dispatcher. I worked for a logging contractor on Vancouver Island's west coast. The off highway trucks, Pacific. Hayes, etc, empty truck and trailer weighs about 75 tons and we found that the ideal load of logs weighed about 100 tons. More than that and the truck could handle it but would go thru brakes and springs and be too slow going up any adverse, so 100 tons worked best and would be 2.5 to 3 times the load a highway log truck could haul.

Working for A Dealship , I worked rebuilding 5 of the KW s planetary drive. Behind the cab were big water tanks with rubber hoses running over the brake drums to cool them off. These videos show the steam comming off the brake drums.

Thats steam from cooling the brakes. The one guy was showing off as he was way over weight. Cool trucks l remember fleets of these. I grew up in logging.