The primer whether Kenworth or Mack etc. seems the same.

However, American semis only have two axles at the rear of the trailer as opposed to 3 on Australian ones.

Could it be that ours spend so much of their time on dead flat country would be loaded with a much heavier load.

Nothing like being behind an Australian Road Train; even worse than a West Texas cotton hauler, or someone hauling cane.

I think you answered your own question.

quote:

Could it be that ours spend so much of their time on dead flat country would be loaded with a much heavier load

That's a lot of it in the logging industry use's more axles and others.

There are some very big rigs on the "Golden Road" in Maine, hauling pulpwood. It is private, with no particular load limits.

You wanna see axles on trailers, you should come to Alberta. Counted 64 on oil field equipment going to FT. Mac. More weight, more axles and tires is the rule.

Grizz

Various states have different size/ weight limits. In the northwest u.s., you can go up to 105,000 lbs or maybe a bit more with eight axles. On some of the toll roads the northeast, you can use two 48-53 foot trailers. For the rest of the states, generally you can only go up to 34,000 lbs on a tandem axle, and 12,500 on the steer axle, to a total of 80,000#.