Truck tyre sizes explained: what 315/80R22.5 means
The size on the sidewall tells you almost everything you need to order the right tyre. Here is how to read the sizes our customers ask for most.
Metric sizes: 315/80R22.5
Many long-haul trucks run a metric size such as 315/80R22.5. Read it in four parts:
- 315 is the width of the tyre in millimetres, measured from sidewall to sidewall.
- 80 is the profile: the sidewall height as a percentage of the width. Here the sidewall is 80% of 315 mm, about 252 mm.
- R means radial construction. Almost every modern truck tyre is radial.
- 22.5 is the rim diameter in inches.
So a 385/65R22.5 is wider (385 mm) with a lower sidewall (65% of the width), on the same 22.5-inch rim. You will see this size on many trailers and steer axles.
Inch sizes: 11R22.5 and 12R22.5
Some sizes still use inches for the width. 11R22.5 is a nominal 11-inch-wide radial tyre on a 22.5-inch rim, and 12R22.5 is about an inch wider. There is no profile number because these sizes have a standard sidewall height.
Older sizes: 9.00R20, 10.00R20 and 11.00R20
Sizes like 9.00R20 follow the same idea: about 9 inches wide, radial, for a 20-inch rim. These are often tube-type tyres, so check whether you need a tube and flap when you order.
Load index and speed rating
After the size you will find a code such as 154/150M. The two numbers are load indices: the first is the load the tyre can carry fitted on its own (single), the second when it runs as one of a pair (dual). The letter is the speed rating. Match or beat the code on the tyres you are replacing.
Steer, drive and trailer
The same size comes in different tread designs for different positions:
- Steer tyres have ribs that run around the tyre, for straight tracking and even wear on the front axle.
- Drive tyres have deep blocks for grip on the axles that push the truck.
- Multi or all position tyres are designed to work on more than one axle, including trailers.
Retreads are sold by pattern name, such as M3 or M103. Each pattern is a tread design for a type of work, and not every pattern comes in every size.
What to send us for a quote
To get an accurate price first time, send us:
- The full size from the sidewall, for example 315/80R22.5.
- The position: steer, drive or trailer.
- How many tyres you need.
- New, stock retread, or retreading your own casings.
You can see our current prices on the new tyres and retreading pages, or send the details on WhatsApp and we will come back to you with a price.