T on a tire: T (temporary spare)
The space saver spare. Restricted speed and restricted distance.
What it changes
A temporary spare is not a tire you finish a journey on and forget about. Its speed symbol is usually M or N (130 or 140 km/h) and the vehicle manufacturer sets a distance limit as well. It is the one category where fitting a lower speed rating than the vehicle's other tires is the design intent rather than a compromise.
Where it sits: Immediately before the section width.
Sizes in this reference with an T 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.
- ST (special trailer) - For trailer axles only. Not for a vehicle that steers or drives.
- C (commercial or van) - A commercial van tire. The C sits after the rim diameter, not before the width.
Questions
- What does T mean on a tire?
- The space saver spare. Restricted speed and restricted distance. A temporary spare is not a tire you finish a journey on and forget about. Its speed symbol is usually M or N (130 or 140 km/h) and the vehicle manufacturer sets a distance limit as well. It is the one category where fitting a lower speed rating than the vehicle's other tires is the design intent rather than a compromise.
- Where does the T appear on the sidewall?
- Immediately before the section width.
- Does a T 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.