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Tyre size calculator
Compare two tyre sizes (e.g., stock 195/65R15 vs upsized 205/55R16). Get diameter, circumference, revolutions per km and speedometer error — decide if a change is safe before you buy.
Stock tyre
195/65R15
Target tyre
205/55R16
Stock
195/65R15
Sidewall height126.8 mm
Overall diameter634.5 mm / 25.0 in
Circumference1,993.3 mm
Revolutions per km502
Target
205/55R16
Sidewall height112.8 mm
Overall diameter631.9 mm / 24.9 in
Circumference1,985.2 mm
Revolutions per km504
✓ Within safe range
Diameter change: -0.4%
Speedo reads 60 km/h
Actual: 59.8 km/h
Diameter difference
-2.6 mm
Rec. max variance
±3%
Most manufacturers specify tyre diameter variance under ±3% to avoid speedometer, ABS, traction control and differential issues. Bigger differences need re-calibration.
Track tyre specs across every vehicle
GetAFix stores exact tyre sizes per vehicle for correct inventory and proper replacement recommendations.