Ariens Track Drive Conversion Kit (921 Series-16 Tires)Ariens Track Drive Conversion Kit (921 Series-16 Tires). Convert Your Ariens Sno-Thro Into A Track Drive Unit. Replace your snow tires with snowmobile-like tracks. Take on slopes and hills like they were flat surfaces. 5-1/2-Inch Wide Directional Snow Track. Delivers more traction for unbeatable maneuverability. Positive-traction design.