6PR — Load Range C
C
Ply rating — casing strength, not a count of plies6-ply rating
An equivalence, not a count: a modern radial at load range C is built to carry what a 6-ply cross-ply once did, with far fewer actual plies. Light truck and van — the first LT step, and the same letter as the European C-type marking without being the same thing.
Standardised by ETRTO or TRA.