Tire size meaning

265/40 R21

What the numbers on a 265/40 R21 tire actually mean — width, sidewall, construction and rim — explained in plain language with real-world driving context.

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Direct answer

What does 265/40 R21 mean?

265/40 R21 is a metric tire size: 265 mm wide, a sidewall 40% of that width (106 mm), radial construction, fitted to a 21-inch wheel. Overall diameter ≈ 745 mm.

265
Section width in mm (sidewall to sidewall).
40
Aspect ratio — sidewall is 40% of width (106 mm).
R
Radial construction — the modern layered build.
21
Wheel rim diameter in inches (533 mm).

Ø 745 mm · 29.35″ · 427 revs/km

Section width 265 mmSidewall 106 mmR21 (533 mm)Ø 745 mm (29.35″)

Dimensional breakdown

Section width
265 mm
Aspect ratio
40%
Sidewall height
106.0 mm
Rim diameter
21″ (533.4 mm)
Overall diameter
745 mm
Circumference
2.342 m
Revs per km
427
Construction
Radial (R)

What 265/40 R21 feels like on the road

A 265/40 R21 tire is a low-profile sporty tire. With a sidewall of 106 mm, it gives precise turn-in with a reasonable ride compromise — typical for sport sedans and hot hatches.

The 265 mm contact width delivers maximum contact patch for high-performance and SUV applications. Combined with a 21-inch wheel, this size is most commonly found on performance SUVs, luxury sedans and aftermarket plus-size setups.

At highway speed each tire completes about 427 revolutions per kilometre — the figure your speedometer and ABS were calibrated against if 265/40 R21 is the OEM specification.

Common alternatives to 265/40 R21

Sizes within ±3% overall diameter — generally safe swaps for speedometer accuracy and clearance. Click any size to open a full side-by-side comparison.

Driver feel · telemetry

What 265/40 R21 usually feels like

A driver-perspective read on this size — steering, comfort, highway stability and rough-road behavior.

Steering feel

Balanced, OEM-style response

A familiar OEM feel — predictable inputs without trade-offs.

Ride comfort

Comfortable daily ride

A balanced compromise — bumps muted, steering still precise.

Highway stability

Planted at highway speed

Wider contact patch resists crosswinds and tramlining — strong straight-line confidence.

Pothole comfort

Reasonable impact protection

Enough sidewall to protect the rim from typical urban hits.

Sporty vs OEM tone

Balanced everyday character

A factory-style balance between feel, comfort and grip.

Sidewall106 mm
Ø745 mm
Width265 mm
Revs/km427

Related tire sizes for 265/40 R21

Explore neighbouring sizes by intent — similar, wider, lower-profile, OEM-safe, or aggressive. Each link opens a full side-by-side comparison.

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Frequently asked questions