245/35R21 tire size

A 245/35R21 tire is 27.75 inches (704.9 mm) tall, 9.65 in (245 mm) wide and fits a 21-inch wheel. In inch notation it is roughly a 27.8x9.6R21 — a "28-inch" tire.

245/35R21 dimensions
Overall diameter	27.75 in	704.9 mm
Section width	9.65 in	245 mm
Sidewall height	3.38 in	85.8 mm
Circumference	87.19 in	2,215 mm
Revolutions	726.7 per mile	451.6 per km
Rim diameter	21 in	533.4 mm

Compare 245/35R21 with another size

Current size

New size

Speed in mphkm/h

Overall diameter difference

−0.07%

60 mph on the speedometer = 60.0 mph actual

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

Ground clearance: −0.3 mm (−0.01 in)
Revolutions: 727 → 727 per mile

245/35R21 285/30R21

Side-by-side dimensions

	Current	New	Difference	%
Diameter	27.75 in	27.73 in	−0.02 in	−0.07%
Diameter	704.9 mm	704.4 mm	−0.5 mm	−0.07%
Width	9.65 in	11.22 in	+1.57 in	+16.33%
Width	245.0 mm	285.0 mm	+40.0 mm	+16.33%
Sidewall	3.38 in	3.37 in	−0.01 in	−0.29%
Sidewall	85.8 mm	85.5 mm	−0.3 mm	−0.29%
Circumference	87.19 in	87.12 in	−0.06 in	−0.07%
Revs per mile	726.7	727.2	+0.5	+0.07%

Speedometer error

Speedometer shows	Actual speed	Difference
20 mph	20.0 mph	0.0 mph
30 mph	30.0 mph	0.0 mph
40 mph	40.0 mph	0.0 mph
50 mph	50.0 mph	0.0 mph
60 mph	60.0 mph	0.0 mph
70 mph	70.0 mph	0.0 mph
80 mph	79.9 mph	−0.1 mph

Alternative sizes on the same 21-inch wheel

Sizes in use within ±3 % of the overall diameter of 245/35R21:

Plus and minus sizes for 245/35R21

Size	Wheel	Diameter	Difference
245/45R19	Minus 2 (19 in)	27.68 in	−0.26%
275/40R19	Minus 2 (19 in)	27.66 in	−0.33%
225/50R19	Minus 2 (19 in)	27.86 in	+0.38%
285/40R19	Minus 2 (19 in)	27.98 in	+0.81%
245/40R20	Minus 1 (20 in)	27.72 in	−0.13%
285/35R20	Minus 1 (20 in)	27.85 in	+0.37%
215/45R20	Minus 1 (20 in)	27.62 in	−0.48%
275/35R20	Minus 1 (20 in)	27.58 in	−0.62%

Vehicles approved with 245/35R21 tires

Models whose Swiss type approval lists 245/35R21 as a standard or optional size (1,326 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 245/35R21 size

245 — section width in millimetres (9.65 in).
35 — aspect ratio: the sidewall is 35 % of the width, 85.8 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.