How do I read a tire size chart?

Find your wheel diameter first — it is the last number in your current size — then read across for overall diameter. Two sizes on the same wheel with overall diameters within 3% of each other are interchangeable as far as the speedometer is concerned.

What is the most common tire size?

On passenger cars, 205/55R16 and 225/45R17 dominate; on crossovers it is 235/65R17 and 245/60R18; on half-ton pickups, 265/70R17 and 275/60R20. Those six cover a large share of what is fitted as original equipment in North America.

Are tire sizes standardized between manufacturers?

The code is standardized, the tire is not. Section width and diameter are nominal design values measured on a specified rim, and real tires routinely differ by several millimeters between brands in the same stated size.

Why does the chart show two revolutions-per-mile figures?

The geometric figure comes from the free diameter and is what speedometer calculations use. Manufacturers publish a loaded figure, measured with the tire under load, which is about 3% higher because the tire deflects.

Reference

Tire Size Chart

Every common size grouped by wheel diameter, with the numbers that matter: overall diameter in inches and millimeters, section width, sidewall height, revolutions per mile and the rim width range the size is designed for. All computed from the ISO size code, so nothing here goes stale.

How to use this chart

Your wheel diameter is the last number in your current size, so start with that block. Sizes within the same block share a wheel and differ only in how much rubber sits around it. Two sizes whose overall diameters are within 3% of each other will read the same on the speedometer to within about 1.8 mph at 60.

The rim width column is the range the size is designed to mount on, derived from the ETRTO relationship between section width and measuring rim. It is an estimate — the tire's own data sheet is authoritative — and it is there because fitting a wide tire on a narrow rim is the most common quiet mistake in a wheel-and-tire package.

14-inch wheel tire sizes

One size, 22.96″ overall diameter.

Tire sizes for 14 inch wheels with computed dimensions
Size	Diameter	Diameter mm	On a tape	Width	Sidewall	Revs / mile	Rim width
175/65R14	22.96″	583	22 15/16″	175 mm	113.7 mm	879	5″–6.5″

15-inch wheel tire sizes

10 sizes, from 24.21″ to 35.00″ overall diameter.

Tire sizes for 15 inch wheels with computed dimensions
Size	Diameter	Diameter mm	On a tape	Width	Sidewall	Revs / mile	Rim width
195/60R15	24.21″	615	24 3/16″	195 mm	117.0 mm	833	5.5″–7″
185/65R15	24.47″	622	24 7/16″	185 mm	120.3 mm	824	5″–6.5″
195/65R15	24.98″	635	25″	195 mm	126.8 mm	807	5.5″–7″
205/65R15	25.49″	648	25 1/2″	205 mm	133.3 mm	791	5.5″–7″
235/75R15	28.88″	734	28 7/8″	235 mm	176.3 mm	698	6″–7.5″
30x9.50R15	30.00″	762	30″	241 mm	190.5 mm	672	6″–8″
31x10.50R15	31.00″	787	31″	267 mm	203.2 mm	651	7″–9″
32x11.50R15	32.00″	813	32″	292 mm	215.9 mm	630	8″–10″
33x12.50R15	33.00″	838	33″	318 mm	228.6 mm	611	9″–11″
35x12.50R15	35.00″	889	35″	318 mm	254.0 mm	576	9″–11″

16-inch wheel tire sizes

9 sizes, from 24.88″ to 32.83″ overall diameter.

Tire sizes for 16 inch wheels with computed dimensions
Size	Diameter	Diameter mm	On a tape	Width	Sidewall	Revs / mile	Rim width
205/55R16	24.88″	632	24 7/8″	205 mm	112.8 mm	811	6″–7.5″
215/55R16	25.31″	643	25 5/16″	215 mm	118.3 mm	797	6.5″–8″
205/60R16	25.69″	652	25 11/16″	205 mm	123.0 mm	785	6″–7.5″
215/60R16	26.16″	664	26 3/16″	215 mm	129.0 mm	771	6″–7.5″
225/60R16	26.63″	676	26 5/8″	225 mm	135.0 mm	757	6.5″–8″
245/75R16	30.47″	774	30 7/16″	245 mm	183.8 mm	662	6.5″–8″
265/70R16	30.61″	777	30 5/8″	265 mm	185.5 mm	659	7.5″–9″
265/75R16	31.65″	804	31 5/8″	265 mm	198.8 mm	637	7″–8.5″
285/75R16	32.83″	834	32 13/16″	285 mm	213.8 mm	614	7.5″–9″

17-inch wheel tire sizes

23 sizes, from 24.97″ to 38.00″ overall diameter.

Tire sizes for 17 inch wheels with computed dimensions
Size	Diameter	Diameter mm	On a tape	Width	Sidewall	Revs / mile	Rim width
225/45R17	24.97″	634	25″	225 mm	101.3 mm	808	7″–8.5″
255/40R17	25.03″	636	25 1/16″	255 mm	102.0 mm	806	8.5″–10″
205/50R17	25.07″	637	25 1/16″	205 mm	102.5 mm	804	6″–7.5″
235/45R17	25.33″	643	25 5/16″	235 mm	105.8 mm	796	7.5″–9″
215/50R17	25.46″	647	25 7/16″	215 mm	107.5 mm	792	6.5″–8″
245/45R17	25.68″	652	25 11/16″	245 mm	110.3 mm	785	7.5″–9″
225/50R17	25.86″	657	25 7/8″	225 mm	112.5 mm	780	7″–8.5″
215/55R17	26.31″	668	26 5/16″	215 mm	118.3 mm	767	6.5″–8″
235/60R17	28.10″	714	28 1/8″	235 mm	141.0 mm	718	6.5″–8″
225/65R17	28.52″	724	28 1/2″	225 mm	146.3 mm	707	6.5″–8″
235/65R17	29.03″	737	29″	235 mm	152.8 mm	695	6.5″–8″
245/65R17	29.54″	750	29 9/16″	245 mm	159.3 mm	683	7″–8.5″
265/65R17	30.56″	776	30 9/16″	265 mm	172.3 mm	660	7.5″–9″
255/70R17	31.06″	789	31 1/16″	255 mm	178.5 mm	649	7″–8.5″
265/70R17	31.61″	803	31 5/8″	265 mm	185.5 mm	638	7.5″–9″
275/70R17	32.16″	817	32 3/16″	275 mm	192.5 mm	627	8″–9.5″
285/70R17	32.71″	831	32 11/16″	285 mm	199.5 mm	617	8″–9.5″
33x12.50R17	33.00″	838	33″	318 mm	203.2 mm	611	9″–11″
295/70R17	33.26″	845	33 1/4″	295 mm	206.5 mm	606	8.5″–10″
315/70R17	34.36″	873	34 3/8″	315 mm	220.5 mm	587	9″–10.5″
35x12.50R17	35.00″	889	35″	318 mm	228.6 mm	576	9″–11″
37x12.50R17	37.00″	940	37″	318 mm	254.0 mm	545	9″–11″
38x13.50R17	38.00″	965	38″	343 mm	266.7 mm	531	10″–12″

18-inch wheel tire sizes

25 sizes, from 25.30″ to 37.00″ overall diameter.

Tire sizes for 18 inch wheels with computed dimensions
Size	Diameter	Diameter mm	On a tape	Width	Sidewall	Revs / mile	Rim width
265/35R18	25.30″	643	25 5/16″	265 mm	92.8 mm	797	8.5″–10″
245/40R18	25.72″	653	25 11/16″	245 mm	98.0 mm	784	8″–9.5″
225/45R18	25.97″	660	26″	225 mm	101.3 mm	777	7″–8.5″
255/40R18	26.03″	661	26 1/16″	255 mm	102.0 mm	775	8.5″–10″
235/45R18	26.33″	669	26 5/16″	235 mm	105.8 mm	766	7.5″–9″
275/40R18	26.66″	677	26 11/16″	275 mm	110.0 mm	756	9″–10.5″
235/50R18	27.25″	692	27 1/4″	235 mm	117.5 mm	740	7″–8.5″
235/55R18	28.18″	716	28 3/16″	235 mm	129.3 mm	716	7″–8.5″
225/60R18	28.63″	727	28 5/8″	225 mm	135.0 mm	704	6.5″–8″
235/60R18	29.10″	739	29 1/8″	235 mm	141.0 mm	693	6.5″–8″
245/60R18	29.57″	751	29 9/16″	245 mm	147.0 mm	682	7″–8.5″
235/65R18	30.03″	763	30″	235 mm	152.8 mm	672	6.5″–8″
255/60R18	30.05″	763	30 1/16″	255 mm	153.0 mm	671	7.5″–9″
265/60R18	30.52″	775	30 1/2″	265 mm	159.0 mm	661	7.5″–9″
265/65R18	31.56″	802	31 9/16″	265 mm	172.3 mm	639	7.5″–9″
255/70R18	32.06″	814	32 1/16″	255 mm	178.5 mm	629	7″–8.5″
275/65R18	32.07″	815	32 1/16″	275 mm	178.8 mm	629	8″–9.5″
285/65R18	32.59″	828	32 9/16″	285 mm	185.3 mm	619	8″–9.5″
265/70R18	32.61″	828	32 5/8″	265 mm	185.5 mm	619	7.5″–9″
33x12.50R18	33.00″	838	33″	318 mm	190.5 mm	611	9″–11″
295/65R18	33.10″	841	33 1/8″	295 mm	191.8 mm	609	8.5″–10″
275/70R18	33.16″	842	33 3/16″	275 mm	192.5 mm	608	8″–9.5″
305/65R18	33.61″	854	33 5/8″	305 mm	198.3 mm	600	8.5″–10″
35x12.50R18	35.00″	889	35″	318 mm	215.9 mm	576	9″–11″
37x12.50R18	37.00″	940	37″	318 mm	241.3 mm	545	9″–11″

19-inch wheel tire sizes

10 sizes, from 25.73″ to 30.04″ overall diameter.

Tire sizes for 19 inch wheels with computed dimensions
Size	Diameter	Diameter mm	On a tape	Width	Sidewall	Revs / mile	Rim width
285/30R19	25.73″	654	25 3/4″	285 mm	85.5 mm	784	9.5″–11″
245/35R19	25.75″	654	25 3/4″	245 mm	85.7 mm	783	8″–9.5″
255/35R19	26.03″	661	26″	255 mm	89.2 mm	775	8.5″–10″
265/35R19	26.30″	668	26 5/16″	265 mm	92.7 mm	767	8.5″–10″
275/35R19	26.58″	675	26 9/16″	275 mm	96.2 mm	759	9″–10.5″
255/50R19	29.04″	738	29 1/16″	255 mm	127.5 mm	695	7.5″–9″
235/55R19	29.18″	741	29 3/16″	235 mm	129.2 mm	691	7″–8.5″
265/50R19	29.43″	748	29 7/16″	265 mm	132.5 mm	685	8″–9.5″
245/55R19	29.61″	752	29 5/8″	245 mm	134.7 mm	681	7″–8.5″
255/55R19	30.04″	763	30 1/16″	255 mm	140.2 mm	671	7.5″–9″

20-inch wheel tire sizes

26 sizes, from 26.75″ to 40.00″ overall diameter.

Tire sizes for 20 inch wheels with computed dimensions
Size	Diameter	Diameter mm	On a tape	Width	Sidewall	Revs / mile	Rim width
245/35R20	26.75″	680	26 3/4″	245 mm	85.8 mm	754	8″–9.5″
295/30R20	26.97″	685	26 15/16″	295 mm	88.5 mm	748	9.5″–11″
255/35R20	27.03″	687	27″	255 mm	89.3 mm	746	8.5″–10″
305/30R20	27.20″	691	27 3/16″	305 mm	91.5 mm	741	10″–11.5″
275/35R20	27.58″	701	27 9/16″	275 mm	96.3 mm	731	9″–10.5″
275/40R20	28.66″	728	28 11/16″	275 mm	110.0 mm	704	9″–10.5″
235/50R20	29.25″	743	29 1/4″	235 mm	117.5 mm	689	7″–8.5″
245/50R20	29.65″	753	29 5/8″	245 mm	122.5 mm	680	7.5″–9″
275/45R20	29.74″	756	29 3/4″	275 mm	123.8 mm	678	8.5″–10″
255/50R20	30.04″	763	30 1/16″	255 mm	127.5 mm	671	7.5″–9″
265/50R20	30.43″	773	30 7/16″	265 mm	132.5 mm	663	8″–9.5″
275/50R20	30.83″	783	30 13/16″	275 mm	137.5 mm	654	8.5″–10″
275/55R20	31.91″	811	31 15/16″	275 mm	151.3 mm	632	8″–9.5″
285/55R20	32.34″	822	32 5/16″	285 mm	156.8 mm	624	8.5″–10″
265/60R20	32.52″	826	32 1/2″	265 mm	159.0 mm	620	7.5″–9″
275/60R20	32.99″	838	33″	275 mm	165.0 mm	611	8″–9.5″
33x12.50R20	33.00″	838	33″	318 mm	165.1 mm	611	9″–11″
305/55R20	33.21″	844	33 3/16″	305 mm	167.8 mm	607	9″–10.5″
285/60R20	33.46″	850	33 7/16″	285 mm	171.0 mm	603	8.5″–10″
295/60R20	33.94″	862	33 15/16″	295 mm	177.0 mm	594	8.5″–10″
275/65R20	34.07″	866	34 1/16″	275 mm	178.8 mm	592	8″–9.5″
285/65R20	34.59″	879	34 9/16″	285 mm	185.3 mm	583	8″–9.5″
35x12.50R20	35.00″	889	35″	318 mm	190.5 mm	576	9″–11″
325/60R20	35.35″	898	35 3/8″	325 mm	195.0 mm	570	9.5″–11″
37x12.50R20	37.00″	940	37″	318 mm	215.9 mm	545	9″–11″
40x13.50R20	40.00″	1,016	40″	343 mm	254.0 mm	504	10″–12″

22-inch wheel tire sizes

4 sizes, from 32.10″ to 34.99″ overall diameter.

Tire sizes for 22 inch wheels with computed dimensions
Size	Diameter	Diameter mm	On a tape	Width	Sidewall	Revs / mile	Rim width
285/45R22	32.10″	815	32 1/8″	285 mm	128.3 mm	628	9″–10.5″
305/45R22	32.81″	833	32 13/16″	305 mm	137.3 mm	615	9.5″–11″
285/50R22	33.22″	844	33 1/4″	285 mm	142.5 mm	607	8.5″–10″
275/60R22	34.99″	889	35″	275 mm	165.0 mm	576	8″–9.5″

The same sizes grouped by vehicle type

Passenger car

15 to 17 inch wheels on saloons, hatchbacks and small estates. Aspect ratios of 45 to 70, where ride comfort still outranks steering response.

175/65R14 · 195/60R15 · 185/65R15 · 205/55R16 · 225/45R17 · 195/65R15 · 205/50R17 · 215/55R16 · 235/45R17 · 215/50R17 · 205/65R15 · 205/60R16 · 225/50R17 · 225/45R18 · 215/60R16 · 215/55R17 · 235/45R18 · 225/60R16 · 235/50R18

Performance

17 to 21 inch wheels with 30 to 45 series sidewalls. Section widths climb fast and the tolerance for diameter error narrows, because these fit inside tight arches.

255/40R17 · 265/35R18 · 245/45R17 · 245/40R18 · 285/30R19 · 245/35R19 · 255/35R19 · 255/40R18 · 265/35R19 · 275/35R19 · 275/40R18 · 245/35R20 · 295/30R20 · 255/35R20 · 305/30R20 · 275/35R20 · 275/40R20

Crossover and SUV

17 to 21 inch wheels on unibody crossovers. The busiest part of the market and the part where plus sizing between trim levels is most common.

235/60R17 · 235/55R18 · 225/65R17 · 225/60R18 · 235/65R17 · 255/50R19 · 235/60R18 · 235/55R19 · 235/50R20 · 265/50R19 · 245/65R17 · 245/60R18 · 245/55R19 · 245/50R20 · 275/45R20 · 235/65R18 · 255/50R20 · 255/55R19 · 255/60R18 · 265/50R20 · 265/60R18 · 275/50R20 · 285/45R22

Light truck

Metric LT sizes on pickups and body-on-frame SUVs. This is where the 3% rule bites hardest, because a two-step size increase usually breaks it.

235/75R15 · 245/75R16 · 265/65R17 · 265/70R16 · 255/70R17 · 265/65R18 · 265/70R17 · 265/75R16 · 275/55R20 · 255/70R18 · 275/65R18 · 275/70R17 · 285/55R20 · 265/60R20 · 285/65R18 · 265/70R18 · 285/70R17 · 305/45R22 · 285/75R16 · 275/60R20 · 295/65R18 · 275/70R18 · 305/55R20 · 285/50R22 · 295/70R17 · 285/60R20 · 305/65R18 · 295/60R20 · 275/65R20 · 315/70R17 · 285/65R20 · 275/60R22 · 325/60R20

Flotation

The inch-based code — 33x12.50R15 — where overall diameter is stated on the sidewall instead of being derived. Off-road sizing lives here.

30x9.50R15 · 31x10.50R15 · 32x11.50R15 · 33x12.50R15 · 33x12.50R17 · 33x12.50R18 · 33x12.50R20 · 35x12.50R15 · 35x12.50R17 · 35x12.50R18 · 35x12.50R20 · 37x12.50R17 · 37x12.50R18 · 37x12.50R20 · 38x13.50R17 · 40x13.50R20

Common questions about the tire size chart

How do I read a tire size chart?: Find your wheel diameter first — it is the last number in your current size — then read across for overall diameter. Two sizes on the same wheel with overall diameters within 3% of each other are interchangeable as far as the speedometer is concerned.
What is the most common tire size?: On passenger cars, 205/55R16 and 225/45R17 dominate; on crossovers it is 235/65R17 and 245/60R18; on half-ton pickups, 265/70R17 and 275/60R20. Those six cover a large share of what is fitted as original equipment in North America.
Are tire sizes standardized between manufacturers?: The code is standardized, the tire is not. Section width and diameter are nominal design values measured on a specified rim, and real tires routinely differ by several millimeters between brands in the same stated size.
Why does the chart show two revolutions-per-mile figures?: The geometric figure comes from the free diameter and is what speedometer calculations use. Manufacturers publish a loaded figure, measured with the tire under load, which is about 3% higher because the tire deflects.

Need a size that is not on this chart? The tire size calculator computes the same figures for any valid code, including flotation sizes such as 33x12.50R15.