Some semi trucks use single axles, while others use double or tandem axles. Here are the differences between the two setups and why they matter.

TORONTO (July 3, 2002) — The Ontario Ministry of Transportation yesterday released details about changes to provincial vehicle weight laws that will phase out the use of non-steerable lift axles on ...

The first ten wheels belong to the tractor. It tows a semi trailer, which usually rides on two rear axles. Those axles also carry four tires each. Add those eight to the tractor’s ten, and you get 18 ...