STAR CUT Foams Tyre Inserts 4 for 2.2 RC Wheels eg AX10 old & Wraith
If you require the tyre to deform and reform slower simply cover one of the two holes drilled in the wheel. (Supplied in 18 star unless 12 is asked for - 12 will make the tyre deform more so better used in those tyres that are stiffer.).