Comparison of tire sizes 225/40 R18 and 205/40 R18
225/40R18
225
Tire width 
40
Profile height 
R18
Tire diameter 
500
RPM per km 225mm90mm637mm2002mm
225
40
18
205
40
18
| Parameters Sizes | Old | New | |||
|---|---|---|---|---|---|
| Diameter, mm | 637 | 621 | -16 (-2.5%) | ||
| Width, mm | 225 | 205 | -20 (-8.9%) | ||
| Circumference, mm | 2002 | 1952 | -50 (-2.5%) | ||
| Profile height, mm | 90 | 82 | -8 (-8.9%) | ||
| RPM per km | 500 | 512 | +12 (+2.4%) | ||
| Clearance change, mm | -8 | ||||
| Result: | The diameter differs by -2.5%. | ||||
| Speedometer reading (km/h) | |
|---|---|
| Real speed (km/h) | 97.5 |
| Difference (km/h) | -2.5 |
Sizes for comparison of tires 225/40 R18
R18
R17 -1
R19 +1
R16 -2
R20 +2
Sizes for comparison of tires 205/40 R18
R18
R17 -1
R19 +1
R16 -2