195/55R18 tire size

A 195/55R18 tire is 26.44 inches (671.7 mm) tall, 7.68 in (195 mm) wide and fits a 18-inch wheel. In inch notation it is roughly a 26.4x7.7R18.

195/55R18 dimensions
Overall diameter	26.44 in	671.7 mm
Section width	7.68 in	195 mm
Sidewall height	4.22 in	107.3 mm
Circumference	83.08 in	2,110 mm
Revolutions	762.6 per mile	473.9 per km
Rim diameter	18 in	457.2 mm

Compare 195/55R18 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: 763 → 762 per mile

195/55R18 215/50R18

Side-by-side dimensions

	Current	New	Difference	%
Diameter	26.44 in	26.46 in	+0.02 in	+0.07%
Diameter	671.7 mm	672.2 mm	+0.5 mm	+0.07%
Width	7.68 in	8.46 in	+0.79 in	+10.26%
Width	195.0 mm	215.0 mm	+20.0 mm	+10.26%
Sidewall	4.22 in	4.23 in	+0.01 in	+0.23%
Sidewall	107.3 mm	107.5 mm	+0.3 mm	+0.23%
Circumference	83.08 in	83.14 in	+0.06 in	+0.07%
Revs per mile	762.6	762.1	−0.6	−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	70.1 mph	+0.1 mph
80 mph	80.1 mph	+0.1 mph

Alternative sizes on the same 18-inch wheel

Sizes in use within ±3 % of the overall diameter of 195/55R18:

Plus and minus sizes for 195/55R18

Size	Wheel	Diameter	Difference
205/65R16	Minus 2 (16 in)	26.49 in	+0.18%
245/55R16	Minus 2 (16 in)	26.61 in	+0.63%
225/60R16	Minus 2 (16 in)	26.63 in	+0.70%
215/60R16	Minus 2 (16 in)	26.16 in	−1.09%
215/55R17	Minus 1 (17 in)	26.31 in	−0.51%
235/50R17	Minus 1 (17 in)	26.25 in	−0.73%
245/50R17	Minus 1 (17 in)	26.65 in	+0.76%
195/60R17	Minus 1 (17 in)	26.21 in	−0.88%
235/40R19	Plus 1 (19 in)	26.40 in	−0.16%
195/50R19	Plus 1 (19 in)	26.68 in	+0.88%
245/40R19	Plus 1 (19 in)	26.72 in	+1.03%
225/40R19	Plus 1 (19 in)	26.09 in	−1.35%
235/35R20	Plus 2 (20 in)	26.48 in	+0.12%
225/35R20	Plus 2 (20 in)	26.20 in	−0.92%
245/35R20	Plus 2 (20 in)	26.75 in	+1.16%
225/40R20	Plus 2 (20 in)	27.09 in	+2.43%

Vehicles approved with 195/55R18 tires

Models whose Swiss type approval lists 195/55R18 as a standard or optional size (31 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 18-inch sizes

Reading the 195/55R18 size

195 — section width in millimetres (7.68 in).
55 — aspect ratio: the sidewall is 55 % of the width, 107.3 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.