Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 235/45-21 | 255/40-21 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 29.33 (744.9) | 29.03 (737.4) | -0.3 (-7.5) -1% |
| Width inches (mm) | 9.25 (235) | 10.04 (255) | 0.79 (20) 8.5% |
| Circum. inches (mm) | 92.13 (2340.17) | 91.21 (2316.61) | -0.93 (-23.56) -1% |
| Sidewall Height inches (mm) | 4.16 (105.75) | 4.02 (102) | -0.15 (-3.75) -3.5% |
| Revolutions per mile (km) | 687.7 (427.32) | 694.7 (431.66) | 6.99 (4.35) 1% |
255/40-21 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 19.8 mph (31.86 km/h) |
| 25 mph (40.23 km/h) | 24.75 mph (39.83 km/h) |
| 30 mph (48.28 km/h) | 29.7 mph (47.79 km/h) |
| 35 mph (56.33 km/h) | 34.65 mph (55.76 km/h) |
| 40 mph (64.37 km/h) | 39.6 mph (63.73 km/h) |
| 45 mph (72.42 km/h) | 44.55 mph (71.69 km/h) |
| 50 mph (80.47 km/h) | 49.5 mph (79.66 km/h) |
| 55 mph (88.51 km/h) | 54.45 mph (87.62 km/h) |
| 60 mph (96.56 km/h) | 59.4 mph (95.59 km/h) |
| 65 mph (104.61 km/h) | 64.35 mph (103.55 km/h) |
| 70 mph (112.65 km/h) | 69.3 mph (111.52 km/h) |
| 75 mph (120.7 km/h) | 74.24 mph (119.49 km/h) |
| 80 mph (128.75 km/h) | 79.19 mph (127.45 km/h) |
| 85 mph (136.79 km/h) | 84.14 mph (135.42 km/h) |
| 90 mph (144.84 km/h) | 89.09 mph (143.38 km/h) |
| 95 mph (152.89 km/h) | 94.04 mph (151.35 km/h) |
| 100 mph (160.93 km/h) | 98.99 mph (159.31 km/h) |
| 2.35 | 2.73 | 2.94 | 3.07 | 3.21 | 3.31 | 3.42 | 3.55 | 3.73 | 3.91 | 4.11 | 4.27 | 4.56 | 4.88 | 5.13 | 5.29 | 5.38 | 5.71 | 6.17 | 7.17 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1768 | 2054 | 2212 | 2310 | 2415 | 2490 | 2573 | 2671 | 2806 | 2941 | 3092 | 3212 | 3430 | 3671 | 3859 | 3980 | 4047 | 4296 | 4642 | 5394 |
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