255/70R15 tire size

A 255/70R15 tire is 29.06 inches (738.0 mm) tall, 10.04 in (255 mm) wide and fits a 15-inch wheel. In inch notation it is roughly a 29.1x10.0R15 — a "29-inch" tire.

255/70R15 dimensions
Overall diameter	29.06 in	738.0 mm
Section width	10.04 in	255 mm
Sidewall height	7.03 in	178.5 mm
Circumference	91.28 in	2,318 mm
Revolutions	694.1 per mile	431.3 per km
Rim diameter	15 in	381.0 mm

Compare 255/70R15 with another size

Current size

New size

Speed in mphkm/h

Overall diameter difference

−0.61%

60 mph on the speedometer = 59.6 mph actual

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

Ground clearance: −2.3 mm (−0.09 in)
Revolutions: 694 → 698 per mile

255/70R15 235/75R15

Side-by-side dimensions

	Current	New	Difference	%
Diameter	29.06 in	28.88 in	−0.18 in	−0.61%
Diameter	738.0 mm	733.5 mm	−4.5 mm	−0.61%
Width	10.04 in	9.25 in	−0.79 in	−7.84%
Width	255.0 mm	235.0 mm	−20.0 mm	−7.84%
Sidewall	7.03 in	6.94 in	−0.09 in	−1.26%
Sidewall	178.5 mm	176.3 mm	−2.3 mm	−1.26%
Circumference	91.28 in	90.72 in	−0.56 in	−0.61%
Revs per mile	694.1	698.4	+4.3	+0.61%

Speedometer error

Speedometer shows	Actual speed	Difference
20 mph	19.9 mph	−0.1 mph
30 mph	29.8 mph	−0.2 mph
40 mph	39.8 mph	−0.2 mph
50 mph	49.7 mph	−0.3 mph
60 mph	59.6 mph	−0.4 mph
70 mph	69.6 mph	−0.4 mph
80 mph	79.5 mph	−0.5 mph

Alternative sizes on the same 15-inch wheel

Sizes in use within ±3 % of the overall diameter of 255/70R15:

Plus and minus sizes for 255/70R15

Size	Wheel	Diameter	Difference
255/65R16	Plus 1 (16 in)	29.05 in	−0.01%
235/70R16	Plus 1 (16 in)	28.95 in	−0.35%
225/75R16	Plus 1 (16 in)	29.29 in	+0.80%
245/70R16	Plus 1 (16 in)	29.50 in	+1.54%
255/60R17	Plus 2 (17 in)	29.05 in	−0.03%
235/65R17	Plus 2 (17 in)	29.03 in	−0.09%
275/55R17	Plus 2 (17 in)	28.91 in	−0.50%
225/70R17	Plus 2 (17 in)	29.40 in	+1.19%
255/55R18	Plus 3 (18 in)	29.04 in	−0.04%
235/60R18	Plus 3 (18 in)	29.10 in	+0.16%
285/50R18	Plus 3 (18 in)	29.22 in	+0.57%
225/60R18	Plus 3 (18 in)	28.63 in	−1.46%

Vehicles approved with 255/70R15 tires

Models whose Swiss type approval lists 255/70R15 as a standard or optional size (64 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 15-inch sizes

Reading the 255/70R15 size

255 — section width in millimetres (10.04 in).
70 — aspect ratio: the sidewall is 70 % of the width, 178.5 mm.
R — radial construction (ZR on the sidewall means a high-speed rated radial; the dimensions are the same).
15 — fits a 15-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.