345/25R21 tire size
345/25R21 is a metric size: 27.8" tall, 13.6" wide, on a 21" rim — about a 28x13.50R21. The sidewall is 3.4" and the tire turns 726 times per mile.
345/25R21 specs
| Overall diameter (height) | 27.79" · 706 mm |
|---|---|
| Section width | 13.58" · 345 mm |
| Sidewall height | 3.40" · 86 mm (25% of width) |
| Rim diameter | 21" |
| Circumference | 87.31" · 2.218 m |
| Revolutions per mile | 726 (451 per km) |
| Inch (flotation) equivalent | 28x13.50R21 |
Equivalent sizes on a 21" rim
Sizes within ±5% of the overall diameter. Green rows are inside the usual ±3% limit for keeping the speedometer, ABS and gearing right; red rows are bigger changes that need clearance checks.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 275/35R21 common | 28.58" | +2.83% | -70 mm | 61.7 mph | calculate → |
| 295/35R21 | 29.13" | +4.82% | -50 mm | 62.9 mph | calculate → |
| 255/40R21 | 29.03" | +4.46% | -90 mm | 62.7 mph | calculate → |
| 265/35R21 | 28.30" | +1.84% | -80 mm | 61.1 mph | calculate → |
| 245/35R21 | 27.75" | -0.14% | -100 mm | 59.9 mph | calculate → |
| 325/30R21 | 28.68" | +3.19% | -20 mm | 61.9 mph | calculate → |
| 255/35R21 | 28.03" | +0.85% | -90 mm | 60.5 mph | calculate → |
| 315/30R21 | 28.44" | +2.34% | -30 mm | 61.4 mph | calculate → |
| 285/35R21 | 28.85" | +3.82% | -60 mm | 62.3 mph | calculate → |
| 245/40R21 | 28.72" | +3.33% | -100 mm | 62.0 mph | calculate → |
| 295/30R21 | 27.97" | +0.64% | -50 mm | 60.4 mph | calculate → |
| 305/30R21 | 28.20" | +1.49% | -40 mm | 60.9 mph | calculate → |
| 285/30R21 | 27.73" | -0.21% | -60 mm | 59.9 mph | calculate → |
| 275/30R21 | 27.50" | -1.06% | -70 mm | 59.4 mph | calculate → |
| 255/30R21 | 27.02" | -2.76% | -90 mm | 58.3 mph | calculate → |
| 355/25R21 | 27.99" | +0.71% | +10 mm | 60.4 mph | calculate → |
| 295/25R21 | 26.81" | -3.54% | -50 mm | 57.9 mph | calculate → |
| 335/30R21 | 28.91" | +4.04% | -10 mm | 62.4 mph | calculate → |
| 265/30R21 | 27.26" | -1.91% | -80 mm | 58.9 mph | calculate → |
| 345/30R21 | 29.15" | +4.89% | 0 mm | 62.9 mph | calculate → |
| 325/25R21 | 27.40" | -1.42% | -20 mm | 59.2 mph | calculate → |
| 305/25R21 | 27.00" | -2.83% | -40 mm | 58.3 mph | calculate → |
| 225/45R21 | 28.97" | +4.25% | -120 mm | 62.5 mph | calculate → |
| 245/30R21 | 26.79" | -3.61% | -100 mm | 57.8 mph | calculate → |
| 275/25R21 | 26.41" | -4.96% | -70 mm | 57.0 mph | calculate → |
Plus / minus sizing: 20" and 22" rims
Same overall height on a different rim. Check wheel width and clearance before switching.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 245/40R20 common | 27.72" | -0.27% | -100 mm | 59.8 mph | calculate → |
| 275/35R20 common | 27.58" | -0.76% | -70 mm | 59.5 mph | calculate → |
| 255/40R20 common | 28.03" | +0.86% | -90 mm | 60.5 mph | calculate → |
| 285/35R20 common | 27.85" | +0.23% | -60 mm | 60.1 mph | calculate → |
| 295/25R22 | 27.81" | +0.06% | -50 mm | 60.0 mph | calculate → |
| 255/30R22 | 28.02" | +0.84% | -90 mm | 60.5 mph | calculate → |
| 335/30R20 | 27.91" | +0.44% | -10 mm | 60.3 mph | calculate → |
| 325/30R20 | 27.68" | -0.41% | -20 mm | 59.8 mph | calculate → |
| 245/30R22 | 27.79" | -0.01% | -100 mm | 60.0 mph | calculate → |
| 215/45R20 | 27.62" | -0.62% | -130 mm | 59.6 mph | calculate → |
| 235/30R22 | 27.55" | -0.86% | -110 mm | 59.5 mph | calculate → |
| 195/50R20 | 27.68" | -0.41% | -150 mm | 59.8 mph | calculate → |
| 285/25R22 | 27.61" | -0.65% | -60 mm | 59.6 mph | calculate → |
| 305/25R22 | 28.00" | +0.76% | -40 mm | 60.5 mph | calculate → |
| 175/55R20 | 27.58" | -0.76% | -170 mm | 59.5 mph | calculate → |
| 165/60R20 | 27.80" | +0.01% | -180 mm | 60.0 mph | calculate → |
| 155/65R20 | 27.93" | +0.51% | -190 mm | 60.3 mph | calculate → |
| 225/45R20 | 27.97" | +0.65% | -120 mm | 60.4 mph | calculate → |
Try another size against 345/25R21
Questions
What size is 345/25R21 in inches?
345/25R21 is about 27.8" tall and 13.6" wide on a 21-inch rim — roughly a 28x13.50R21 in inch sizing.
What does 345/25R21 mean?
345 mm section width, sidewall 25% of the width (3.40"), radial construction, 21-inch rim.
What tire sizes are equivalent to 345/25R21?
On the same 21" rim, within 3% of the diameter: 245/35R21 (-0.14%), 285/30R21 (-0.21%), 295/30R21 (+0.64%), 355/25R21 (+0.71%), 255/35R21 (+0.85%), 275/30R21 (-1.06%).
How many revolutions per mile does a 345/25R21 tire make?
About 726 revolutions per mile (circumference 87.3").
How these numbers are computed
Diameter = rim + 2 × sidewall, sidewall = width × aspect ÷ 100, circumference = π × diameter, revolutions per mile = 63,360 ÷ circumference. Real tires differ by brand by a few tenths of an inch. Last reviewed October 14, 2026.