Flange nut with full metallic locking that has a small skull (10 mm) to fit in the rims.
It is important to change these at regular intervals so that the nuts retain their locking force.
Use an impact wrench when screwing the tires on the kart, but be careful not to use a too heavy machine. Usually a small 10-12v machine will be ok. The risk of you tight too hard and the stud bolts going off instead.
The all-metal locking is a requirement for international races so that the locking should not disappear from any heat from the axle or rim.
Skull size: 10 mm