Tiré du site de Motoz:
What S/T, H/T, I/T means.
S/T = Soft terrain (loose, sandy loam, pine forest, clay) great traction, shorter wear life.
I/T = Intermediate (mix of everything) all round traction, medium wear life.
I-H/T = Between Intermediate and Hard Terrain (hi speed Safari - Outback). Long wear life.
H/T = Hard Terrain (gravel roads, rocky fire trails, hard pack desert and sand). Extreme.
In other words, Soft, Middle, Hard and Extreme Hard.