Simple enough, as these types of semi-trucks have eighteen wheels. Each cargo container has sixteen wheels supporting its weight. The cab of the eighteen wheeler contains ten wheels, but eight of them are already supporting the cargo container. In total, there are eighteen wheels on an average size semi-truck.
Eighteen wheelers suffer the same types of problems that cause semi-trucks accidents. They face problems with rollovers, loss of control, traveling too fast, long hours, and other types of accidents.