This is a pair of Pro-Line Step Pin 2.2" off-road truck tires in M3 compound. The Step Pin tread is designed for loamy track conditions and works best when the track is wet. The drier the track, the harder the compound of tire you should use (ie: M3 when very wet, M2 when dry). However if the track is very dusty, you should generally use a softer compound tire.

Pro-Line truck tires are generally available in M2, M3 and R3 compounds. The M2 compound is the hardest compound and will provide the longest tire life and works best on hard packed, dry tracks with high traction. If the track is wetter or less hard packed, the M3 compound tires will provide better grip with decent wear, but will generally wear faster than M2 compound tires. The new R3 rubber compound was designed by Pro-Line to provide the traction of the M3 compound yet the wear characteristics of the M2 compound. The R3 compound generally seems to work best on hard packed, blue groove tracks and is not a good all purpose tire compound (note that not all tire treads are available in R3 compound).