How to Read Your Tyre Sidewall

That string of numbers on your tyre — like 225/45R17 91W — tells you everything you need to know.

Example: 225/45R17 91W

225 — Width in mm

The section width (sidewall to sidewall) is 225 millimetres.

45 — Aspect ratio

Sidewall height is 45% of the width — so 225 x 0.45 = 101 mm tall sidewall.

Low numbers (35, 40) = sporty/firm. High numbers (60, 70) = comfort/SUV.

R — Construction

R = Radial. Almost all modern tyres. (You might rarely see D for bias-ply on trailers.)

17 — Rim diameter in inches

This tyre fits a 17-inch wheel.

91 — Load index

91 = max load of 615 kg per tyre. Look up the load-index chart — never fit a tyre with a LOWER load index than your placard.

W — Speed rating

W = up to 270 km/h. Common speed ratings:

• T = 190 km/h (older sedans)
• H = 210 km/h (most family cars)
• V = 240 km/h (performance sedans)
• W = 270 km/h (performance/luxury)
• Y = 300 km/h (sports cars)

Never fit a tyre with a LOWER speed rating than original — your insurance may be void.

Other useful sidewall info

• DOT code (4 digits): week and year of manufacture. e.g. 2424 = 24th week of 2024.
• Treadwear / Traction / Temperature: UTQG rating — higher treadwear = longer life.
• M+S or 3PMSF snowflake: mud + snow / severe snow rating.
• Made in...: country of manufacture.
• MAX PSI: the maximum the tyre can hold. NOT your recommended pressure (see door placard for that).

Need to find your size?

Look at the sidewall of any existing tyre, or check the placard inside the driver's door. Call us on 0466 004 999 with the code and we will check stock.