Comparison of tire sizes 275/45 R21 and 255/55 R20
275/45R21
275
Tire width 
45
Profile height 
R21
Tire diameter 
408
RPM per km 275mm124mm781mm2453mm
275
45
21
255
55
20
| Parameters Sizes | Old | New | |||
|---|---|---|---|---|---|
| Diameter, mm | 781 | 789 | +8 (+1%) | ||
| Width, mm | 275 | 255 | -20 (-7.3%) | ||
| Circumference, mm | 2453 | 2477 | +24 (+1%) | ||
| Profile height, mm | 124 | 140 | +16 (+12.9%) | ||
| RPM per km | 408 | 404 | -4 (-1%) | ||
| Clearance change, mm | +4 | ||||
| Result: | The diameter differs by 1%. | ||||
| Speedometer reading (km/h) | |
|---|---|
| Real speed (km/h) | 101 |
| Difference (km/h) | 1 |
Sizes for comparison of tires 275/45 R21
R21
R20 -1
R22 +1
R19 -2
Sizes for comparison of tires 255/55 R20
R20
R19 -1
R21 +1
R18 -2
R22 +2