But fitting a differential to a kart would be expensive, it’s against the rules, and it would totally change everything about karting. This makes turning very difficult.​ Cars deal with this situation with a differential, which allows the rear wheels to spin at different speeds. If both rear tires are planted on the ground and you try to turn, the inner tire will spin across the ground too fast and it will push the inside of the kart in a straight line. But what about the back wheels? They are stuck together by the solid rear axle and must spin at exactly the same rate. On a kart, this is easily done by the front wheels because they are independent and free spinning. The tighter the turn, the bigger the difference in the wheel speeds.

Because of this, the inner tires travel less distance, and therefore they need to spin slower than the outer tires.

The outer ones go through a larger arc than the inner ones. When both cars and karts negotiate a turn, the outer and inner wheels go through different arcs.