255/40R23 tire size
255/40R23 is a metric size: 31.0" tall, 10.0" wide, on a 23" rim — about a 31x10.00R23. The sidewall is 4.0" and the tire turns 650 times per mile.
255/40R23 specs
| Overall diameter (height) | 31.03" · 788 mm |
|---|---|
| Section width | 10.04" · 255 mm |
| Sidewall height | 4.02" · 102 mm (40% of width) |
| Rim diameter | 23" |
| Circumference | 97.49" · 2.476 m |
| Revolutions per mile | 650 (404 per km) |
| Inch (flotation) equivalent | 31x10.00R23 |
Equivalent sizes on a 23" 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 | |
|---|---|---|---|---|---|
| 285/35R23 | 30.85" | -0.57% | +30 mm | 59.7 mph | calculate → |
| 295/35R23 | 31.13" | +0.32% | +40 mm | 60.2 mph | calculate → |
| 315/30R23 | 30.44" | -1.90% | +60 mm | 58.9 mph | calculate → |
| 325/30R23 | 30.68" | -1.14% | +70 mm | 59.3 mph | calculate → |
| 325/35R23 | 31.96" | +2.98% | +70 mm | 61.8 mph | calculate → |
| 335/30R23 | 30.91" | -0.38% | +80 mm | 59.8 mph | calculate → |
| 305/35R23 | 31.41" | +1.21% | +50 mm | 60.7 mph | calculate → |
| 275/40R23 | 31.66" | +2.03% | +20 mm | 61.2 mph | calculate → |
| 275/35R23 | 30.58" | -1.46% | +20 mm | 59.1 mph | calculate → |
Try another size against 255/40R23
Questions
What size is 255/40R23 in inches?
255/40R23 is about 31.0" tall and 10.0" wide on a 23-inch rim — roughly a 31x10.00R23 in inch sizing.
What does 255/40R23 mean?
255 mm section width, sidewall 40% of the width (4.02"), radial construction, 23-inch rim.
What tire sizes are equivalent to 255/40R23?
On the same 23" rim, within 3% of the diameter: 295/35R23 (+0.32%), 335/30R23 (-0.38%), 285/35R23 (-0.57%), 325/30R23 (-1.14%), 305/35R23 (+1.21%), 275/35R23 (-1.46%).
How many revolutions per mile does a 255/40R23 tire make?
About 650 revolutions per mile (circumference 97.5").
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.