Comparison of tire sizes 155/70 R12 and 145/70 R12

155/70R12
155 Tire width
70 Profile height
R12 Tire diameter
610 RPM per km
155mm109mm522mm1639mm
155
70
12
145
70
12
Parameters Sizes Old New
Diameter, mm522508-14 (-2.7%)
Width, mm155145-10 (-6.5%)
Circumference, mm16391595-44 (-2.7%)
Profile height, mm109102-7 (-6.4%)
RPM per km610627+17 (+2.8%)
Clearance change, mm-7
Result:
The diameter differs by -2.7%.
Speedometer reading (km/h)
Real speed (km/h)97.3
Difference (km/h)-2.7

Sizes for comparison of tires 155/70 R12

R12
R13 +1
R14 +2

Sizes for comparison of tires 145/70 R12

R12
R13 +1