Comparison of tire sizes 155/70 R12 and 175/60 R13

155/70R12
155 Tire width
70 Profile height
R12 Tire diameter
610 RPM per km
155mm109mm522mm1639mm
155
70
12
175
60
13
Parameters Sizes Old New
Diameter, mm522540+18 (+3.4%)
Width, mm155175+20 (+12.9%)
Circumference, mm16391697+58 (+3.5%)
Profile height, mm109105-4 (-3.7%)
RPM per km610589-21 (-3.4%)
Clearance change, mm+9
Result:
The diameter differs by 3.4%.
Speedometer reading (km/h)
Real speed (km/h)103.5
Difference (km/h)3.5

Sizes for comparison of tires 155/70 R12

R12
R13 +1
R14 +2

Sizes for comparison of tires 175/60 R13

R13
R12 -1
R14 +1
R15 +2