W speed rating
A tire marked W is rated to 270 km/h, which is 168 mph.
A speed symbol is the maximum speed the tire is rated for when it is correctly inflated, undamaged, in sound condition, and carrying no more than the load its load index allows. It is a rating, not a recommendation, and it never overrides the speed limit where you are driving.
- Rated
- 270 km/h
- Rated
- 168 mph
- Sources
- 8
ZR and the W symbol
ZR is not a speed symbol. It sits inside the size (255/40ZR18), not in the service description, and marks a tire built for sustained use above 240 km/h. When a ZR tire also prints a service description, the letter in that service description is the rating: 255/40ZR18 95Y is a 300 km/h tire. A ZR size with no service description carries no published ceiling on this table, and the tire manufacturer is the only authority on its maximum.
ZR on its own marks a tire built for sustained use above 240 km/h (149 mph). It is a construction marking inside the size, not a row in the speed table.
Where W sits
See the whole table, in speed order and alphabetically.
Questions about the W rating
- What does a W speed rating mean?
- A W rated tire is rated to 270 km/h (168 mph) under the standard's test conditions, when it is correctly inflated, undamaged and carrying no more than its load index allows.
- Is W a fast enough rating for me?
- That is set by the vehicle, not by the tire. The placard in the driver's door jamb states the speed rating the vehicle was built around, and a replacement should meet or exceed it. Local law may also require it. This site reproduces the published table and approves nothing.
- Where does W sit in the table?
- V (240 km/h (149 mph)) is directly below it. Y (300 km/h (186 mph)) is directly above it. The table is not alphabetical: H sits between U and V because H was once the top rating and the letters above it were added later.
Where these figures come from
Computed on this page, not looked up. Each figure and the arithmetic behind it:
- Miles per hour
miles per hour = kilometres per hour x 0.621371192237, rounded to the nearest mile per hour
Published values here were read from 8 independent sources:
- Tire Speed Rating Chart: Speed Symbols and Maximum Speeds - AmesWeb, undated reference chart (read 2026-08-27)Speed symbols A1 to Y, kilometres per hour
- Speed Ratings - CJ Tire, undated reference chart (read 2026-08-27)Speed symbols A1 to Y in km/h and mph, plus Z, (W) and (Y)
- Tire Speed Rating Chart (A1 to Y) - Your Auto Vision, 2026 revision (read 2026-08-27)Speed symbols A1 to Y in km/h and mph, plus Z, ZR and (Y)
- Tire Speed Rating Chart - TireGuide.org, undated reference chart (read 2026-08-27)Speed symbols L to Y in km/h and mph, plus ZR
- Tire Speed Rating Chart & Meaning - TireReference, undated reference guide (read 2026-08-27)Speed symbols L to Y in km/h and mph; ZR handling
- Tire Speed Rating Chart - Santa Ana Wheel, undated reference article (read 2026-08-27)Speed symbols L to Y in km/h and mph, plus (Y) and the ZR designation
- Load Index & Weight Ratings - rimlist, undated reference article (read 2026-08-27)Speed symbols L to Y in km/h and mph, plus (Y) and ZR
- How to Read Speed Rating, Load Index and Service Descriptions - HP Wizard, reproduces Tire Rack tire tech information (read 2026-08-27)Speed symbols L to Y in km/h and mph; ZR and bracketed symbols with worked sidewall examples
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.