Comparison of tire sizes 225/45 R17 and 205/40 R18
225/45R17
225
Tire width 
45
Profile height 
R17
Tire diameter 
502
RPM per km 225mm101mm634mm1993mm
225
45
17
205
40
18
| Parameters Sizes | Old | New | |||
|---|---|---|---|---|---|
| Diameter, mm | 634 | 621 | -13 (-2.1%) | ||
| Width, mm | 225 | 205 | -20 (-8.9%) | ||
| Circumference, mm | 1993 | 1952 | -41 (-2.1%) | ||
| Profile height, mm | 101 | 82 | -19 (-18.8%) | ||
| RPM per km | 502 | 512 | +10 (+2%) | ||
| Clearance change, mm | -7 | ||||
| Result: | The diameter differs by -2.1%. | ||||
| Speedometer reading (km/h) | |
|---|---|
| Real speed (km/h) | 97.9 |
| Difference (km/h) | -2.1 |
Sizes for comparison of tires 225/45 R17
R17
R16 -1
R18 +1
R15 -2
R19 +2
Sizes for comparison of tires 205/40 R18
R18
R17 -1
R19 +1
R16 -2