Definitions of SAE Classifications
SAE CLASS "S"
Regular (non-reinforced) passenger tire chains and cables for vehicles with restricted wheel well clearances.
1.46" clearance on tread-face, 0.59" clearance on side-wall
SAE CLASS "U"
Regular (non-reinforced) and lug reinforced passenger tire chains for vehicles with regular (non-restricted) wheel well clearances.
1.97" clearance on tread-face, 0.91" clearance on side-wall
SAE CLASS "W"
Those passenger tire chains that use light truck components, as well as some light truck chains.
2.50" clearance on tread face, 1.50" clearance on side-wall