315/25R21 tire size in inches
A 315/25R21 tire measures
27.2" tall × 12.4" wide
3.10" sidewall on a 21" wheel. 741 revolutions per mile.
315/25R21 means a tire 315 mm wide, with sidewalls 25% as tall as the tire is wide (79 mm), radial construction (R), for a 21 inch wheel.
315/25R21 specs
| Overall diameter (height) | 27.20 inches (691 mm) |
|---|---|
| Section width | 12.40 inches (315 mm) |
| Sidewall height | 3.10 inches (79 mm) |
| Wheel (rim) diameter | 21 inches |
| Circumference | 85.5 inches (2,171 mm) |
| Revolutions per mile | 741 |
| Revolutions per kilometer | 461 |
| Approximate rim width | 10.5" to 12.0" |
| In inches (flotation style) | 27.2x12.4R21 |
| Aspect ratio | 25% |
Calculated from the size. Real tires differ by brand, model and tread depth, typically by a few tenths of an inch.
Sizes that can replace 315/25R21 on a 21" wheel
These 21" sizes are within 3% of 315/25R21's overall diameter, the range most tire shops treat as interchangeable.
| Size | Diameter | Width | Difference | Real speed at 60 | |
|---|---|---|---|---|---|
| 225/35R21 | 27.20" | 8.86" | 0.0% | 60.0 mph | Compare |
| 265/30R21 | 27.26" | 10.43" | +0.2% | 60.1 mph | Compare |
| 255/30R21 | 27.02" | 10.04" | −0.7% | 59.6 mph | Compare |
| 305/25R21 | 27.00" | 12.01" | −0.7% | 59.6 mph | Compare |
| 325/25R21 | 27.40" | 12.80" | +0.7% | 60.4 mph | Compare |
| 235/35R21 | 27.48" | 9.25" | +1.0% | 60.6 mph | Compare |
| 275/30R21 | 27.50" | 10.83" | +1.1% | 60.7 mph | Compare |
| 295/25R21 | 26.81" | 11.61" | −1.4% | 59.1 mph | Compare |
| 335/25R21 | 27.59" | 13.19" | +1.4% | 60.9 mph | Compare |
| 245/30R21 | 26.79" | 9.65" | −1.5% | 59.1 mph | Compare |
| 285/30R21 | 27.73" | 11.22" | +2.0% | 61.2 mph | Compare |
| 245/35R21 | 27.75" | 9.65" | +2.0% | 61.2 mph | Compare |
Same height on other wheel sizes (plus and minus sizing)
| Size | Wheel | Diameter | Difference | |
|---|---|---|---|---|
| 185/70R17 | 17" | 27.20" | 0.0% | Compare |
| 305/30R20 | 20" | 27.20" | 0.0% | Compare |
| 195/60R18 | 18" | 27.21" | 0.0% | Compare |
| 265/25R22 | 22" | 27.22" | +0.1% | Compare |
| 285/50R16 | 16" | 27.22" | +0.1% | Compare |
| 235/55R17 | 17" | 27.18" | −0.1% | Compare |
| 225/80R13 | 13" | 27.17" | −0.1% | Compare |
| 335/35R18 | 18" | 27.23" | +0.1% | Compare |
| 215/60R17 | 17" | 27.16" | −0.2% | Compare |
| 235/50R18 | 18" | 27.25" | +0.2% | Compare |
| 345/30R19 | 19" | 27.15" | −0.2% | Compare |
| 295/35R19 | 19" | 27.13" | −0.3% | Compare |
One size up or down
- 305/25R21narrower: 27.0" × 12.0"
- 325/25R21wider: 27.4" × 12.8"
- 315/30R21taller sidewall: 28.4" × 12.4"
Compare 315/25R21 with another size
Questions
- How tall is a 315/25R21 tire?
- A 315/25R21 tire is 27.2 inches tall (691 mm), calculated from the size. It is 12.4 inches wide with 3.1 inches sidewalls. Real tires vary by a few tenths of an inch between brands and tread patterns.
- What does 315/25R21 mean?
- 315/25R21 means a tire 315 mm wide, with sidewalls 25% as tall as the tire is wide (79 mm), radial construction (R), for a 21 inch wheel.
- How many revolutions per mile does a 315/25R21 tire make?
- About 741 revolutions per mile, based on a circumference of 85.5 inches. Under load the tire flattens slightly, so the maker's published figure is usually a little higher.
- What rim width fits a 315/25R21 tire?
- Roughly 10.5" to 12.0". Check the tire maker's approved rim range for the exact model before buying wheels.
- Can I use 225/35R21 instead of 315/25R21?
- 225/35R21 is 0.00 inches (0.0%) in overall diameter, so at an indicated 60 mph you would be doing 60.0 mph. Differences under 3% are usually fine, but check clearance, load index and your vehicle's placard.