These AC10 tyres are superb! ROAD LEGAL MX Tyres which are superb for Trial riding and also events where you can use MX Tyres. A good alternative to the S12... Can NOT Be used in FIM approved only events such as BEC etc. 110/100/18" or 120/90/18" We recommend the 120 size only on big 4 strokes. The 110 size is ideal for any 2 stroke.