275/65R18 tire size in inches
A 275/65R18 tire is 32.07 inches tall and 10.83 inches wide on a 18-inch rim. These are nominal dimensions from the official sizing formula.
| Dimension | 275/65R18 | This size vs yours | |
|---|---|---|---|
| Overall diameter UN R30 §6.1.2.1 | 32.07 in 814.7 mm | ||
| Section width UN R30 §6.1.2.1 | 10.83 in 275.0 mm | ||
| Sidewall height UN R30 §6.1.2.1 | 7.04 in 178.8 mm | ||
| Rim diameter Marked on the tire | 18 in | ||
| Circumference From diameter | 100.77 in | ||
| Revolutions per mile From diameter | 629 | ||
| Allowed real diameter UN R30 §6.1.5 | 31.65–32.64 in |
Is 275/65R18 a 32-inch tire?
Yes. At 32.07 inches tall, 275/65R18 is commonly called a 32-inch tire. Inch-class names round to the nearest inch; the true nominal height is 32.07 in, and a new tire may legally measure between 31.65 and 32.64 in.
Speedometer change
Example: if your speedometer is calibrated for 285/65R18 and you fit 275/65R18, the tire is −1.6% in diameter, so your true speed differs from the reading as shown below. Enter your current size above to see your own figures.
| Reading | True speed | Difference |
|---|---|---|
| 30 mph | 29.5 mph | −0.5 mph |
| 45 mph | 44.3 mph | −0.7 mph |
| 55 mph | 54.1 mph | −0.9 mph |
| 60 mph | 59.1 mph | −0.9 mph |
| 70 mph | 68.9 mph | −1.1 mph |
| 80 mph | 78.7 mph | −1.3 mph |
Sizes within 3% of 275/65R18
These sizes are within 3% of the diameter of 275/65R18. The 3% figure is a rule of thumb, not a regulation and not a fitment check: wheel width, offset, suspension and body clearance decide what fits. See changing tire size.
| Size | Diameter (in) | Width (in) | Change | ±3% | Ride height (in) |
|---|---|---|---|---|---|
| 245/75R17 | 31.47 | 9.65 | −1.9% | −0.30 | |
| 265/65R18 | 31.56 | 10.43 | −1.6% | −0.26 | |
| 265/70R17 | 31.61 | 10.43 | −1.5% | −0.23 | |
| 265/75R16 | 31.65 | 10.43 | −1.3% | −0.21 | |
| 235/85R16 | 31.73 | 9.25 | −1.1% | −0.17 | |
| 275/55R20 | 31.91 | 10.83 | −0.5% | −0.08 | |
| 255/75R17 | 32.06 | 10.04 | 0.0% | −0.01 | |
| 275/65R18 | 32.07 | 10.83 | — | — | |
| 275/70R17 | 32.16 | 10.83 | +0.3% | +0.04 | |
| 285/55R20 | 32.34 | 11.22 | +0.8% | +0.13 | |
| 265/60R20 | 32.52 | 10.43 | +1.4% | +0.22 | |
| 33x12.50R15 | 32.52 | 12.52 | +1.4% | +0.22 | |
| 285/65R18 | 32.59 | 11.22 | +1.6% | +0.26 | |
| 265/70R18 | 32.61 | 10.43 | +1.7% | +0.27 | |
| 285/70R17 | 32.71 | 11.22 | +2.0% | +0.32 | |
| 295/55R20 | 32.78 | 11.61 | +2.2% | +0.35 | |
| 305/70R16 | 32.81 | 12.01 | +2.3% | +0.37 | |
| 285/75R16 | 32.83 | 11.22 | +2.4% | +0.38 | |
| 275/60R20 | 32.99 | 10.83 | +2.9% | +0.46 | |
| 33x12.50R17 | 33.00 | 12.50 | +2.9% | +0.46 |
Inch equivalent of 275/65R18
In inch terms, 275/65R18 is about 32.1x10.8R18: 32.1 in tall and 10.8 in wide, a 32-inch tire.
| Inch size | Diameter (in) | Change | Width (in) | Dimensions from |
|---|---|---|---|---|
| 33x12.50R18 | 33.00 | +2.9% | 12.50 | numbers in the size |
| 33x12.50R15 | 32.52 | +1.4% | 12.52 | UN R54 table |
| 33x9.50R15 | 32.52 | +1.4% | 9.45 | UN R54 table |
| 32x11.50R15 | 31.54 | −1.7% | 11.42 | UN R54 table |
How 275/65R18 is calculated
275 mm section width × 65% aspect ratio = 178.8 mm sidewall (7.04 in).
Overall diameter = rim + 2 × sidewall = 18 in + 2 × 7.04 in = 32.07 in.
Formula: UN Regulation No. 30 §2.15 and §6.1.2.1 (passenger) and UN Regulation No. 54 §6.1.2.1 (light truck). Revolutions per mile = 63,360 ÷ circumference. Full sources are listed at the end of this page.
Questions about 275/65R18
- How tall is a 275/65R18 tire?
- 32.07 inches (814.7 mm) nominal. A new tire may measure from 31.65 to 32.64 in under the official tolerance; the maker's specification gives the figure for a specific tire.
- How wide is a 275/65R18 tire?
- 10.83 inches (275.0 mm) section width. Overall width can be slightly larger; for passenger tires, US rule FMVSS 139 allows 7% over the specified width (or 10 mm, if larger, for some pressure classes).
- How many revolutions per mile does 275/65R18 make?
- About 629 nominal, from a circumference of 100.77 in. Tire makers publish measured revolutions per mile for each tire.
- Will 275/65R18 fit my vehicle?
- This page can't tell you. Check the tire size on your door-jamb placard, then confirm wheel width, offset and clearance with the tire or vehicle maker.
Related
- All 18" sizes
- All 275 mm sizes
- 275/65R18 vs 285/65R18
- 275/65R18 vs 265/70R18
- Tire size chart
- Wheel offset calculator
- Re-gear calculator
- Plus-size calculator
Printed from https://tiresizecalc.net/size/275-65r18/. Figures as published on 2026-11-01. The full working and the official sources are on that page.
Sources
This size is listed by the manufacturer: Goodyear Wrangler Fortitude HT, checked on the manufacturer's site on 2026-11-01. The size page shows nominal figures, not that product's measurements.
- 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. 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 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.
- 49 CFR 571.139 - Standard No. 139; New pneumatic radial tires for light vehicles. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations (eCFR). 49 CFR 571.139. eCFR up to date as of 2026-10-15. S6.1.2: passenger tire width up to 7 percent (or 10 mm) over the specified width. Retrieved 2026-11-01.
- 49 CFR 571.110 - Standard No. 110; Tire selection and rims for motor vehicles with a GVWR of 4,536 kilograms (10,000 pounds) or less. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations, annual edition (GovInfo). 2006-10-01. S4.3: the door placard shows the original tire size. 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.