Comparison of tire sizes 155/70 R12 and 165/55 R14

155/70R12
155 Tire width
70 Profile height
R12 Tire diameter
610 RPM per km
155mm109mm522mm1639mm
155
70
12
165
55
14
Parameters Sizes Old New
Diameter, mm522537+15 (+2.9%)
Width, mm155165+10 (+6.5%)
Circumference, mm16391687+48 (+2.9%)
Profile height, mm10991-18 (-16.5%)
RPM per km610593-17 (-2.8%)
Clearance change, mm+8
Result:
The diameter differs by 2.9%.
Speedometer reading (km/h)
Real speed (km/h)102.9
Difference (km/h)2.9

Sizes for comparison of tires 155/70 R12

R12
R13 +1
R14 +2

Sizes for comparison of tires 165/55 R14

R14
R13 -1
R15 +1
R12 -2