Kikki's Workshop Q&A: Let's ask Kikki ! Kikki's Workshop
Why does an articulated dump truck have 6 tires unlike regular cars? What will happen if it only has two tires in the rear ?
Each tire can only hold a limited amount of weight. If you take out two tires in the middle, the remaining tires could not support the weight of the truck. Also Articulated Dump Trucks run on soft soil and slippery roads by driving all six tires. It would not run well on those surfaces without the added traction of the middle tires.

Articulate dump trucks have six tires in total on right and left.