8 wheeler has 8 sets of wheels, 4 axles x 2, twin wheels count as one wheel.
six wheel tractor unit has three axles x 2 equals six wheeler.
eighteen wheeler is an americanism, count the actual wheels, two axles on trailer x 4 wheels on each + two driven axles on tractor unit with 4 wheels on each one steering axle x 2 wheels steering all adds up to 18 wheels a hummin.
European trailers now have 'super single' wheels instead of twins on three axles, hope that makes sense
six wheel tractor unit has three axles x 2 equals six wheeler.
eighteen wheeler is an americanism, count the actual wheels, two axles on trailer x 4 wheels on each + two driven axles on tractor unit with 4 wheels on each one steering axle x 2 wheels steering all adds up to 18 wheels a hummin.
European trailers now have 'super single' wheels instead of twins on three axles, hope that makes sense