Comparison of tire sizes 155/70 R12 and 145/70 R13
155/70R12
155
Tire width 
70
Profile height 
R12
Tire diameter 
610
RPM per km 155mm109mm522mm1639mm
155
70
12
145
70
13
| Parameters Sizes | Old | New | |||
|---|---|---|---|---|---|
| Diameter, mm | 522 | 533 | +11 (+2.1%) | ||
| Width, mm | 155 | 145 | -10 (-6.5%) | ||
| Circumference, mm | 1639 | 1675 | +36 (+2.2%) | ||
| Profile height, mm | 109 | 102 | -7 (-6.4%) | ||
| RPM per km | 610 | 597 | -13 (-2.1%) | ||
| Clearance change, mm | +6 | ||||
| Result: | The diameter differs by 2.1%. | ||||
| Speedometer reading (km/h) | |
|---|---|
| Real speed (km/h) | 102.2 |
| Difference (km/h) | 2.2 |
Sizes for comparison of tires 155/70 R12
R12
R13 +1
R14 +2
Sizes for comparison of tires 145/70 R13
R13
R12 -1
R14 +1