Comparison of tire sizes 255/35 R18 and 245/40 R17
255/35R18
255
Tire width 
35
Profile height 
R18
Tire diameter 
501
RPM per km 255mm89mm636mm1997mm
255
35
18
245
40
17
| Parameters Sizes | Old | New | |||
|---|---|---|---|---|---|
| Diameter, mm | 636 | 628 | -8 (-1.3%) | ||
| Width, mm | 255 | 245 | -10 (-3.9%) | ||
| Circumference, mm | 1997 | 1972 | -25 (-1.3%) | ||
| Profile height, mm | 89 | 98 | +9 (+10.1%) | ||
| RPM per km | 501 | 507 | +6 (+1.2%) | ||
| Clearance change, mm | -4 | ||||
| Result: | The diameter differs by -1.3%. | ||||
| Speedometer reading (km/h) | |
|---|---|
| Real speed (km/h) | 98.7 |
| Difference (km/h) | -1.3 |
Sizes for comparison of tires 255/35 R18
R18
R17 -1
R19 +1
R16 -2
R20 +2
Sizes for comparison of tires 245/40 R17
R17
R16 -1
R18 +1
R15 -2
R19 +2