Comparison of tire sizes 235/70 R17 and 245/55 R18
235/70R17
235
Tire width 
70
Profile height 
R17
Tire diameter 
418
RPM per km 235mm165mm761mm2390mm
235
70
17
245
55
18
| Parameters Sizes | Old | New | |||
|---|---|---|---|---|---|
| Diameter, mm | 761 | 727 | -34 (-4.5%) | ||
| Width, mm | 235 | 245 | +10 (+4.3%) | ||
| Circumference, mm | 2390 | 2283 | -107 (-4.5%) | ||
| Profile height, mm | 165 | 135 | -30 (-18.2%) | ||
| RPM per km | 418 | 438 | +20 (+4.8%) | ||
| Clearance change, mm | -17 | ||||
| Result: | The diameter differs by -4.5%. | ||||
| Speedometer reading (km/h) | |
|---|---|
| Real speed (km/h) | 95.5 |
| Difference (km/h) | -4.5 |
Sizes for comparison of tires 235/70 R17
R17
R16 -1
R18 +1
R15 -2
R19 +2
Sizes for comparison of tires 245/55 R18
R18
R17 -1
R19 +1
R16 -2
R20 +2