Load range, ply rating & load index
Type a load index (146 or 146/143) or a load range letter (G) from the sidewall.
Load range and ply rating
Load range is a letter; ply rating is the older “number of plies” way to express the same strength. Modern tires don't literally have that many plies.
Load range letters and ply ratings per The Tire and Rim Association; G (14), H (16), J (18) and L (20) confirmed in the Apollo 2023 and Bridgestone truck data books. The load a tire carries depends on its size and pressure — see the size pages and your tire maker's load & inflation table.
What 146/143 means
Truck tires show two load indexes: the first for single mounting, the second for each tire in a dual pair (lower, because duals share load unevenly). The letter after them is the speed symbol (L = 75 mph / 120 km/h).
Load index table (ISO 4000 / ETRTO / TRA) from the Continental Agricultural Tires Technical Databook, cross-checked with the Bridgestone truck tire data book — 70 indexes compared, no differences. Checked October 2026.