After the size on a truck tire sidewall comes a short code like 146/143 L. That is the service description, and it is the tire's working limit: what one tire carries mounted single, what it carries as part of a dual pair, and the speed it can hold at that load. Get it wrong and nothing else about the tire matters.
Load index: the two weight numbers
Each number is an index into a standardized load table. These are the anchors that come up on the sizes we sell — 11R22.5, 11R24.5, 285/75R24.5 and 295/75R22.5:
- 141 = 5,675 lb per tire
- 143 = 6,005 lb per tire
- 144 = 6,175 lb per tire
- 146 = 6,610 lb per tire
- 147 = 6,780 lb per tire
- 149 = 7,160 lb per tire
So 146/143 L reads 6,610 lb single, 6,005 lb each in duals. A 149/146 L 11R24.5 reads 7,160 lb single and 6,610 lb dual.
Why the dual number is lower
Two tires bolted together never split the load evenly. Road crown, a few psi of difference between them, uneven tread depth, one casing that took a curb — any of it puts more weight on one tire than the other. The rating standards build that in by derating each tire in a dual pair, so the pair still has margin on a bad day. Four tires on a drive axle is four times the dual number, not four times the single number.
Speed symbol: the letter
The letter caps the speed the tire can sustain at its rated load. Highway truck tires use two:
- L — 75 mph
- M — 81 mph
Most linehaul TBR is rated L. Never fit below the symbol your equipment calls for.
Load range G and H
Truck tires state a load range rather than a ply count. G is a 14 ply rating, H is 16. No modern radial actually carries fourteen fabric plies — it is a strength equivalent, and it travels with a higher maximum inflation pressure, which is where the extra capacity comes from. The same size in both ranges carries different service descriptions: an 11R22.5 is commonly 144/142 L in G and 146/143 L in H.
Match it to the axle, not to a guess
Work from your gross axle weight ratings and the tire information on the truck or trailer placard, then divide by the number of tires on that axle. Steer is the tight one — two tires under a loaded front end, so the single number does the work there, which is what steer and all-position tires are built for. Drive and trailer positions run duals, so the second number governs.
Every product page in the commercial catalog prints the full service description alongside ply, load range, max load single and dual, max pressure and tread depth. If the size itself is what's throwing you, start with reading the sidewall. Still unsure, send your axle ratings and positions with the quote request and a human checks fitment before any invoice goes out — talk to us first.