Comparison of tire sizes 275/70 R18 and 255/70 R18
275/70R18
275
Tire width 
70
Profile height 
R18
Tire diameter 
378
RPM per km 275mm193mm842mm2646mm
275
70
18
255
70
18
| Parameters Sizes | Old | New | |||
|---|---|---|---|---|---|
| Diameter, mm | 842 | 814 | -28 (-3.3%) | ||
| Width, mm | 275 | 255 | -20 (-7.3%) | ||
| Circumference, mm | 2646 | 2558 | -88 (-3.3%) | ||
| Profile height, mm | 193 | 179 | -14 (-7.3%) | ||
| RPM per km | 378 | 391 | +13 (+3.4%) | ||
| Clearance change, mm | -14 | ||||
| Result: | The diameter differs by -3.3%. | ||||
| Speedometer reading (km/h) | |
|---|---|
| Real speed (km/h) | 96.7 |
| Difference (km/h) | -3.3 |
Sizes for comparison of tires 275/70 R18
R18
R17 -1
R16 -2
R20 +2
Sizes for comparison of tires 255/70 R18
R18
R17 -1
R19 +1
R16 -2
R20 +2