Comparison of tire sizes 255/45 R20 and 265/40 R21
255/45R20
255
Tire width 
45
Profile height 
R20
Tire diameter 
432
RPM per km 255mm115mm738mm2317mm
255
45
20
265
40
21
| Parameters Sizes | Old | New | |||
|---|---|---|---|---|---|
| Diameter, mm | 738 | 745 | +7 (+0.9%) | ||
| Width, mm | 255 | 265 | +10 (+3.9%) | ||
| Circumference, mm | 2317 | 2342 | +25 (+1.1%) | ||
| Profile height, mm | 115 | 106 | -9 (-7.8%) | ||
| RPM per km | 432 | 427 | -5 (-1.2%) | ||
| Clearance change, mm | +4 | ||||
| Result: | The diameter differs by 0.9%. | ||||
| Speedometer reading (km/h) | |
|---|---|
| Real speed (km/h) | 101.1 |
| Difference (km/h) | 1.1 |
Sizes for comparison of tires 255/45 R20
R20
R19 -1
R21 +1
R18 -2
R22 +2
Sizes for comparison of tires 265/40 R21
R21
R20 -1
R22 +1
R19 -2
