225/75R15 tire size in inches
A 225/75R15 tire is 28.29 inches tall and 8.86 inches wide on a 15-inch rim. These are nominal dimensions from the official sizing formula.
| Dimension | 225/75R15 | This size vs yours | |
|---|---|---|---|
| Overall diameter UN R30 §6.1.2.1 | 28.29 in 718.5 mm | ||
| Section width UN R30 §6.1.2.1 | 8.86 in 225.0 mm | ||
| Sidewall height UN R30 §6.1.2.1 | 6.64 in 168.8 mm | ||
| Rim diameter Marked on the tire | 15 in | ||
| Circumference From diameter | 88.87 in | ||
| Revolutions per mile From diameter | 713 | ||
| Allowed real diameter UN R30 §6.1.5 | 27.89–28.82 in |
Is 225/75R15 a 28-inch tire?
Yes. At 28.29 inches tall, 225/75R15 is commonly called a 28-inch tire. Inch-class names round to the nearest inch; the true nominal height is 28.29 in, and a new tire may legally measure between 27.89 and 28.82 in.
Speedometer change
Example: if your speedometer is calibrated for 235/75R15 and you fit 225/75R15, the tire is −2.0% 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 | 29.4 mph | −0.6 mph |
| 45 mph | 44.1 mph | −0.9 mph |
| 55 mph | 53.9 mph | −1.1 mph |
| 60 mph | 58.8 mph | −1.2 mph |
| 70 mph | 68.6 mph | −1.4 mph |
| 80 mph | 78.4 mph | −1.6 mph |
Sizes within 3% of 225/75R15
These sizes are within 3% of the diameter of 225/75R15. 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) |
|---|---|---|---|---|---|
| 225/75R15 | 28.29 | 8.86 | — | — | |
| 235/75R15 | 28.88 | 9.25 | +2.1% | +0.30 | |
| 235/65R17 | 29.03 | 9.25 | +2.6% | +0.37 |
Inch equivalent of 225/75R15
In inch terms, 225/75R15 is about 28.3x8.9R15: 28.3 in tall and 8.9 in wide, a 28-inch tire.
| Inch size | Diameter (in) | Change | Width (in) | Dimensions from |
|---|---|---|---|---|
| 29x9.50R15 | 28.50 | +0.8% | 9.45 | UN R54 table |
| 28x8.50R15 | 27.52 | −2.7% | 8.58 | UN R54 table |
| 30x9.50R15 | 29.53 | +4.4% | 9.45 | UN R54 table |
How 225/75R15 is calculated
225 mm section width × 75% aspect ratio = 168.8 mm sidewall (6.64 in).
Overall diameter = rim + 2 × sidewall = 15 in + 2 × 6.64 in = 28.29 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 225/75R15
- How tall is a 225/75R15 tire?
- 28.29 inches (718.5 mm) nominal. A new tire may measure from 27.89 to 28.82 in under the official tolerance; the maker's specification gives the figure for a specific tire.
- How wide is a 225/75R15 tire?
- 8.86 inches (225.0 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 225/75R15 make?
- About 713 nominal, from a circumference of 88.87 in. Tire makers publish measured revolutions per mile for each tire.
- Will 225/75R15 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
Printed from https://tiresizecalc.net/size/225-75r15/. 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: Toyo Open Country A/T III, 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.
- 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.