265/45R21 tire size

A 265/45R21 tire is 30.39 inches (771.9 mm) tall, 10.43 in (265 mm) wide and fits a 21-inch wheel. In inch notation it is roughly a 30.4x10.4R21 — a "30-inch" tire.

265/45R21 dimensions
Overall diameter	30.39 in	771.9 mm
Section width	10.43 in	265 mm
Sidewall height	4.69 in	119.3 mm
Circumference	95.47 in	2,425 mm
Revolutions	663.6 per mile	412.4 per km
Rim diameter	21 in	533.4 mm

Compare 265/45R21 with another size

Current size

New size

Speed in mphkm/h

Overall diameter difference

−0.32%

60 mph on the speedometer = 59.8 mph actual

Within the ±3 % diameter range most tire fitters accept.

Ground clearance: −1.3 mm (−0.05 in)
Revolutions: 664 → 666 per mile

265/45R21 295/40R21

Side-by-side dimensions

	Current	New	Difference	%
Diameter	30.39 in	30.29 in	−0.10 in	−0.32%
Diameter	771.9 mm	769.4 mm	−2.5 mm	−0.32%
Width	10.43 in	11.61 in	+1.18 in	+11.32%
Width	265.0 mm	295.0 mm	+30.0 mm	+11.32%
Sidewall	4.69 in	4.65 in	−0.05 in	−1.05%
Sidewall	119.3 mm	118.0 mm	−1.3 mm	−1.05%
Circumference	95.47 in	95.16 in	−0.31 in	−0.32%
Revs per mile	663.6	665.8	+2.2	+0.32%

Speedometer error

Speedometer shows	Actual speed	Difference
20 mph	19.9 mph	−0.1 mph
30 mph	29.9 mph	−0.1 mph
40 mph	39.9 mph	−0.1 mph
50 mph	49.8 mph	−0.2 mph
60 mph	59.8 mph	−0.2 mph
70 mph	69.8 mph	−0.2 mph
80 mph	79.7 mph	−0.3 mph

Alternative sizes on the same 21-inch wheel

Sizes in use within ±3 % of the overall diameter of 265/45R21:

Plus and minus sizes for 265/45R21

Size	Wheel	Diameter	Difference
265/55R19	Minus 2 (19 in)	30.48 in	+0.29%
235/60R19	Minus 2 (19 in)	30.10 in	−0.95%
255/55R19	Minus 2 (19 in)	30.04 in	−1.14%
275/55R19	Minus 2 (19 in)	30.91 in	+1.71%
265/50R20	Minus 1 (20 in)	30.43 in	+0.14%
295/45R20	Minus 1 (20 in)	30.45 in	+0.21%
235/55R20	Minus 1 (20 in)	30.18 in	−0.70%
285/45R20	Minus 1 (20 in)	30.10 in	−0.96%
265/40R22	Plus 1 (22 in)	30.35 in	−0.14%
295/35R22	Plus 1 (22 in)	30.13 in	−0.86%
275/40R22	Plus 1 (22 in)	30.66 in	+0.89%
315/35R22	Plus 1 (22 in)	30.68 in	+0.96%
315/30R23	Plus 2 (23 in)	30.44 in	+0.17%
275/35R23	Plus 2 (23 in)	30.58 in	+0.62%
285/35R23	Plus 2 (23 in)	30.85 in	+1.53%
255/40R23	Plus 2 (23 in)	31.03 in	+2.11%

Vehicles approved with 265/45R21 tires

Models whose Swiss type approval lists 265/45R21 as a standard or optional size (333 approvals in total). Always check your own vehicle's placard or papers.

Source: Swiss Federal Roads Office (FEDRO/ASTRA), open government data. Original data (downloaded 2026-09-29). Data processed by us; errors in processing are ours, not the publisher's.

Nearby 21-inch sizes

Reading the 265/45R21 size

265 — section width in millimetres (10.43 in).
45 — aspect ratio: the sidewall is 45 % of the width, 119.3 mm.
R — radial construction (ZR on the sidewall means a high-speed rated radial; the dimensions are the same).
21 — fits a 21-inch diameter wheel.

The load index and speed rating (for example 91V) follow the size on the sidewall. They must meet at least the values on your vehicle's tire placard.