275/70R18 tire size

A 275/70R18 tire is 33.16 inches (842.2 mm) tall, 10.83 in (275 mm) wide and fits a 18-inch wheel. In inch notation it is roughly a 33.2x10.8R18 — a "33-inch" tire.

275/70R18 dimensions
Overall diameter	33.16 in	842.2 mm
Section width	10.83 in	275 mm
Sidewall height	7.58 in	192.5 mm
Circumference	104.17 in	2,646 mm
Revolutions	608.3 per mile	378.0 per km
Rim diameter	18 in	457.2 mm

Compare 275/70R18 with another size

Current size

New size

Speed in mphkm/h

Overall diameter difference

−1.66%

60 mph on the speedometer = 59.0 mph actual

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

Ground clearance: −7.0 mm (−0.28 in)
Revolutions: 608 → 619 per mile

275/70R18 265/70R18

Side-by-side dimensions

	Current	New	Difference	%
Diameter	33.16 in	32.61 in	−0.55 in	−1.66%
Diameter	842.2 mm	828.2 mm	−14.0 mm	−1.66%
Width	10.83 in	10.43 in	−0.39 in	−3.64%
Width	275.0 mm	265.0 mm	−10.0 mm	−3.64%
Sidewall	7.58 in	7.30 in	−0.28 in	−3.64%
Sidewall	192.5 mm	185.5 mm	−7.0 mm	−3.64%
Circumference	104.17 in	102.44 in	−1.73 in	−1.66%
Revs per mile	608.3	618.5	+10.3	+1.69%

Speedometer error

Speedometer shows	Actual speed	Difference
20 mph	19.7 mph	−0.3 mph
30 mph	29.5 mph	−0.5 mph
40 mph	39.3 mph	−0.7 mph
50 mph	49.2 mph	−0.8 mph
60 mph	59.0 mph	−1.0 mph
70 mph	68.8 mph	−1.2 mph
80 mph	78.7 mph	−1.3 mph

Alternative sizes on the same 18-inch wheel

Sizes in use within ±3 % of the overall diameter of 275/70R18:

Plus and minus sizes for 275/70R18

Size	Wheel	Diameter	Difference
285/75R16	Minus 2 (16 in)	32.83 in	−0.99%
285/70R17	Minus 1 (17 in)	32.71 in	−1.35%
305/55R20	Plus 2 (20 in)	33.21 in	+0.15%
275/60R20	Plus 2 (20 in)	32.99 in	−0.50%
285/60R20	Plus 2 (20 in)	33.46 in	+0.93%
265/60R20	Plus 2 (20 in)	32.52 in	−1.92%

Nearby 18-inch sizes

Reading the 275/70R18 size

275 — section width in millimetres (10.83 in).
70 — aspect ratio: the sidewall is 70 % of the width, 192.5 mm.
R — radial construction (ZR on the sidewall means a high-speed rated radial; the dimensions are the same).
18 — fits a 18-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.