Tire size converter
Convert a metric tire size to inches, or an inch size such as 33x12.50R15 to its nearest metric sizes. Type a size; the result updates as you type.
285/70R17 = 32.7x11.2R17
32.71 in tall, 11.22 in wide, 7.85 in sidewall, on a 17 in rim.
| Inch size | Diameter (in) | Change | Dimensions from |
|---|---|---|---|
| 33x12.50R17 | 33.00 | +0.9% | numbers in the size |
| 33x12.50R15 | 32.52 | −0.6% | UN R54 table |
| 33x9.50R15 | 32.52 | −0.6% | UN R54 table |
Metric to inch: the 40 most-searched sizes
Inch figures are nominal, from the official sizing formula. The last column is the nearest inch (flotation) size in our list.
| Metric size | In inches | Diameter (in) | Width (in) | Nearest inch size |
|---|---|---|---|---|
| 205/50R15 | 23.1x8.1R15 | 23.07 | 8.07 | 24x7.50R13 (+1.9%) |
| 235/75R15 | 28.9x9.2R15 | 28.88 | 9.25 | 29x9.50R15 (−1.3%) |
| 245/75R16 | 30.5x9.7R16 | 30.47 | 9.65 | 31x10.50R15 (+0.1%) |
| 265/70R16 | 30.6x10.4R16 | 30.61 | 10.43 | 31x10.50R15 (−0.3%) |
| 265/75R16 | 31.6x10.4R16 | 31.65 | 10.43 | 32x11.50R15 (−0.4%) |
| 235/85R16 | 31.7x9.2R16 | 31.73 | 9.25 | 32x11.50R15 (−0.6%) |
| 305/70R16 | 32.8x12.0R16 | 32.81 | 12.01 | 33x12.50R17 (+0.6%) |
| 285/75R16 | 32.8x11.2R16 | 32.83 | 11.22 | 33x12.50R17 (+0.5%) |
| 315/75R16 | 34.6x12.4R16 | 34.60 | 12.40 | 35x12.50R15 (−0.2%) |
| 235/65R17 | 29.0x9.2R17 | 29.03 | 9.25 | 30x9.50R15 (+1.7%) |
| 245/70R17 | 30.5x9.7R17 | 30.50 | 9.65 | 31x10.50R15 (0.0%) |
| 265/65R17 | 30.6x10.4R17 | 30.56 | 10.43 | 31x10.50R15 (−0.2%) |
| 245/75R17 | 31.5x9.7R17 | 31.47 | 9.65 | 32x11.50R15 (+0.2%) |
| 265/70R17 | 31.6x10.4R17 | 31.61 | 10.43 | 32x11.50R15 (−0.2%) |
| 255/75R17 | 32.1x10.0R17 | 32.06 | 10.04 | 33x12.50R15 (+1.4%) |
| 275/70R17 | 32.2x10.8R17 | 32.16 | 10.83 | 33x12.50R15 (+1.1%) |
| 285/70R17 | 32.7x11.2R17 | 32.71 | 11.22 | 33x12.50R15 (−0.6%) |
| 295/70R17 | 33.3x11.6R17 | 33.26 | 11.61 | 33x12.50R17 (−0.8%) |
| 305/70R17 | 33.8x12.0R17 | 33.81 | 12.01 | 35x12.50R15 (+2.1%) |
| 285/75R17 | 33.8x11.2R17 | 33.83 | 11.22 | 35x12.50R15 (+2.1%) |
| 315/70R17 | 34.4x12.4R17 | 34.36 | 12.40 | 35x12.50R15 (+0.5%) |
| 225/45R18 | 26.0x8.9R18 | 25.97 | 8.86 | 27x8.50R14 (+2.2%) |
| 265/65R18 | 31.6x10.4R18 | 31.56 | 10.43 | 32x11.50R15 (−0.1%) |
| 275/65R18 | 32.1x10.8R18 | 32.07 | 10.83 | 33x12.50R15 (+1.4%) |
| 285/65R18 | 32.6x11.2R18 | 32.59 | 11.22 | 33x12.50R15 (−0.2%) |
| 265/70R18 | 32.6x10.4R18 | 32.61 | 10.43 | 33x12.50R15 (−0.3%) |
| 275/70R18 | 33.2x10.8R18 | 33.16 | 10.83 | 33x12.50R17 (−0.5%) |
| 285/70R18 | 33.7x11.2R18 | 33.71 | 11.22 | 33x12.50R17 (−2.1%) |
| 325/65R18 | 34.6x12.8R18 | 34.63 | 12.80 | 35x12.50R15 (−0.3%) |
| 285/75R18 | 34.8x11.2R18 | 34.83 | 11.22 | 35x12.50R20 (+0.5%) |
| 275/55R20 | 31.9x10.8R20 | 31.91 | 10.83 | 32x11.50R15 (−1.2%) |
| 285/55R20 | 32.3x11.2R20 | 32.34 | 11.22 | 33x12.50R15 (+0.5%) |
| 265/60R20 | 32.5x10.4R20 | 32.52 | 10.43 | 33x12.50R15 (0.0%) |
| 295/55R20 | 32.8x11.6R20 | 32.78 | 11.61 | 33x12.50R17 (+0.7%) |
| 275/60R20 | 33.0x10.8R20 | 32.99 | 10.83 | 33x12.50R17 (0.0%) |
| 305/55R20 | 33.2x12.0R20 | 33.21 | 12.01 | 33x12.50R17 (−0.6%) |
| 285/60R20 | 33.5x11.2R20 | 33.46 | 11.22 | 33x12.50R17 (−1.4%) |
| 275/65R20 | 34.1x10.8R20 | 34.07 | 10.83 | 35x12.50R15 (+1.3%) |
| 285/65R20 | 34.6x11.2R20 | 34.59 | 11.22 | 35x12.50R15 (−0.2%) |
| 295/65R20 | 35.1x11.6R20 | 35.10 | 11.61 | 35x12.50R20 (−0.3%) |
How the conversion works
For a metric size, the sidewall is the width in millimeters times the aspect ratio, divided by 25.4 to get inches. The diameter is the rim plus two sidewalls. 285/70R17 is 285 × 0.70 ÷ 25.4 = 7.85 in of sidewall, so 17 + 2 × 7.85 = 32.71 in tall. See how to read a tire size.
For an inch size, the numbers in the name are rounded. Where UN Regulation No. 54 lists the size, we use its table: 33x12.50R15LT is 32.52 in tall. See inch tire sizes.
No metric size is an exact match for an inch size. Compare diameters, then check width and load index; neither the converter nor any chart tells you whether a tire fits your vehicle.
Printed from https://tiresizecalc.net/converter/. Figures as published on 2026-11-01. The full working and the official sources are on that page.
Sources
- UN Regulation No. 30 - Uniform provisions concerning the approval of pneumatic tyres for motor vehicles and their trailers (Revision 3). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.29/Rev.3. 2007-03-29. Para 2.15 and 6.1.2.1: aspect ratio and outer diameter, D = d + 2H. Retrieved 2026-11-01.
- UN Regulation No. 54 - Uniform provisions concerning the approval of pneumatic tyres for commercial vehicles and their trailers (Revision 2). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.53/Rev.2. 2004-04-16. Para 6.1.2.1: the same formula for light truck tires. Retrieved 2026-11-01.
- UN Regulation No. 30 - Uniform provisions concerning the approval of pneumatic tyres for motor vehicles and their trailers (Revision 3). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.29/Rev.3. 2007-03-29. Para 6.1.5: allowed outer diameter, Dmin = d + 2H x 0.97, Dmax = d + 2H x 1.04. Retrieved 2026-11-01.
- UN Regulation No. 54 - Uniform provisions concerning the approval of pneumatic tyres for commercial vehicles and their trailers (Revision 2). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.53/Rev.2. 2004-04-16. Annex 5 Part II Table B: design outer diameter and section width of 33x12.50R15LT, 33x12.50R15LT. Retrieved 2026-11-01.
- UN Regulation No. 54 - Uniform provisions concerning the approval of pneumatic tyres for commercial vehicles and their trailers (Revision 2). United Nations Economic Commission for Europe (UNECE). E/ECE/324 E/ECE/TRANS/505 Rev.1/Add.53/Rev.2. 2004-04-16. Para 6.1.5.1, 6.1.5.3.1 and Table B note 2: allowed outer diameter for table sizes. Retrieved 2026-11-01.
- Computed by tiresizecalc.net from the cited formula. Sri Murugan Systems. Not in UN R54 Annex 5 Table B: diameter and width of 33x12.50R17, 33x12.50R20, 33x12.50R18, 35x12.50R20 are the numbers in the size. Retrieved 2026-11-01.
- Computed by tiresizecalc.net from the cited formula. Sri Murugan Systems. Circumference = pi x diameter; revolutions per mile = 63,360 / circumference; 1 in = 25.4 mm exactly. Retrieved 2026-11-01.
Last reviewed 2026-11-01. The full source list, with dates and file checksums, is in How the numbers are calculated. To report an error, email contactus@tiresizecalc.net.