Comparison of tire sizes 155/70 R12 and 135/80 R13

155/70R12
155 Tire width
70 Profile height
R12 Tire diameter
610 RPM per km
155mm109mm522mm1639mm
155
70
12
135
80
13
Parameters Sizes Old New
Diameter, mm522546+24 (+4.6%)
Width, mm155135-20 (-12.9%)
Circumference, mm16391716+77 (+4.7%)
Profile height, mm109108-1 (-0.9%)
RPM per km610583-27 (-4.4%)
Clearance change, mm+12
Result:
The diameter differs by 4.6%.
Speedometer reading (km/h)
Real speed (km/h)104.7
Difference (km/h)4.7

Sizes for comparison of tires 155/70 R12

R12
R13 +1
R14 +2

Sizes for comparison of tires 135/80 R13

R13
R14 +1
R15 +2