ST on a tire: ST (special trailer)
For trailer axles only. Not for a vehicle that steers or drives.
What it changes
Trailer axles neither steer nor transmit drive torque, and ST tires are built for that narrower job: high sustained load at lower speed. They carry more load than a passenger tire of similar size and are not appropriate on a car or truck.
Where it sits: Immediately before the section width.
Sizes in this reference with an ST prefix
The other prefixes
The prefix decides which load table rates the tire, so the same numbers after it do not mean the same capacity.
- P-metric (passenger) - A passenger car tire rated against the North American Tire and Rim Association tables.
- Euro-metric (no prefix) - No letter at all. The tire is rated against the European tyre and rim organisation tables.
- LT-metric (light truck) - Built for light truck duty, and rated for it without any derating.
- T (temporary spare) - The space saver spare. Restricted speed and restricted distance.
- C (commercial or van) - A commercial van tire. The C sits after the rim diameter, not before the width.
Questions
- What does ST mean on a tire?
- For trailer axles only. Not for a vehicle that steers or drives. Trailer axles neither steer nor transmit drive torque, and ST tires are built for that narrower job: high sustained load at lower speed. They carry more load than a passenger tire of similar size and are not appropriate on a car or truck.
- Where does the ST appear on the sidewall?
- Immediately before the section width.
- Does a ST tire take the 1.10 light truck derating?
- No. The 1.10 factor applies to P-metric and Euro-metric tires fitted to a light truck. It is not the rating scheme this type is rated under.
Where these figures come from
Published values here were read from 2 independent sources:
- Tire code - Wikipedia, revision read 27 August 2026 (read 2026-08-27)Service type letters, construction letters, load range letters and ply ratings, sidewall marking glossary
- Load Index & Weight Ratings - rimlist, undated reference article (read 2026-08-27)LT against P-metric fitment, ST trailer tires, SL, XL and HL reference pressures
These are independent publishers, not independent measurements. Each one reproduces a table originally set by a standards body, so agreement between them shows a value was transcribed correctly, not that the underlying table is right. Where a figure is safety relevant, check it against the tire manufacturer's own data before relying on it.