(Eli5) Why do Buses & Trucks use 2 skinny wheels put together on each side of the axle? Instead of just using one fat wheel?

Question

(Eli5) Why do Buses & Trucks use 2 skinny wheels put together on each side of the axle? Instead of just using one fat wheel?

In: Engineering

Answer 1

Actually the two axels on the back of a full size bus in the US, the front ones, the drive wheels, of the two are dual wheels and tires and the rear of the two are just one wheel and tire called a tag axle. Some makes, like Prevost, this tag axle can be lifted by air pressure thus shorting the turning radius and increasing pressure on the four drive wheels.