A 40 mm diameter axle improves a kart’s grip under braking

"Compared to the more common 50 mm diameter axles, a 40mm diameter axle frees up the chassis more. This allows greater speed when exiting bends, but it negatively impacts braking, during which the back of the chassis lowers and there is a loss of grip. To prevent this from happening, it is necessary to modify the entire chassis set-up. However, the fact remains that with the same set-up a 40 mm diameter axle worsens throttle off compared to a 50 mm diameter axle".