This is the Pro Molded Inner Foam Inserts for 24mm Tires from HPI|
Rubber tire inserts.
Helps increase grip and stability of tires.
Prevents tires from caving in during high speed & cornering.
Green / Medium
Two rubber inserts
Width: 18mm (13/16")
Outside Diameter: 60mm (2-3/8")
Inside Diameter: 46mm (1-13/16")
This is installed between the tire and wheel so they resist moving
while the car is cornering. For really high-grip tracks, use
a firmer tire insert in the front with a softer insert in the rear.