Calculate Tyre Size Deviation & Speedometer Reading
WHEELS 'N CUSTOMS
AUTOMOTIVE TOOL: INTERACTIVE ROLLING CIRCUMFERENCE & SPEEDOMETER ERROR CALCULATOR
Rolling Circumference Calculator for Tyres & Wheels
When you choose a larger wheel size or a different tyre size, the total outer diameter of the wheel changes. An excessive deviation in the rolling circumference directly affects the accuracy of your speedometer, the odometer, the operation of safety systems (ABS/ESP) and can lead to APK rejection in the Netherlands and Belgium.
With our professional Rolling Circumference Calculator you can calculate within seconds the exact differences in single and total sidewall height, outer diameter, rolling circumference, ground clearance and the actual speeds (at 30, 50, 80, 100, 120 and 130 km/h) between your original factory size and your new wheel setup.
Calculate Your Tyre Size Deviation & Speeds
1. Original Tyre Size (OEM)
2. New Tyre Size (Setup)
Fitment Status & APK Advice: The deviation falls within the safe legal tolerance of -2% to +1.5%. This tyre size is an excellent fit!
Specification / Parameter
Original (OEM)
New (Setup)
Difference / Deviation
Single Sidewall Height (1x side)
101.3 mm
90.0 mm
-11.3 mm
Total Sidewall Height (2x sides) *
202.5 mm
180.0 mm
-22.5 mm
Total Outside Diameter
634.3 mm
637.2 mm
+2.9 mm
Rolling Circumference (Total Rolling Distance)
1992.7 mm
2001.8 mm
+9.1 mm
Change in Ground Clearance / Ride Height
0.0 mm (Reference)
+1.5 mm
Car sits higher/lower
Actual Speed at 30 km/h on Speedometer
30.0 km/h
30.1 km/h
+0.46 %
Actual Speed at 50 km/h on Speedometer
50.0 km/h
50.2 km/h
+0.46 %
Actual Speed at 80 km/h on Speedometer
80.0 km/h
80.4 km/h
+0.46 %
Actual Speed at 100 km/h on Speedometer
100.0 km/h
100.5 km/h
+0.46 %
Actual Speed at 120 km/h on Speedometer
120.0 km/h
120.5 km/h
+0.46 %
Actual Speed at 130 km/h on Speedometer
130.0 km/h
130.6 km/h
+0.46 %
* Sidewall Height Explanation: The Single Sidewall Height is the physical thickness of one side of the tyre (from the rim edge to the tread). The Total Sidewall Height is the sum of the bottom and top together that is used for calculating the total wheel diameter.
1. Legal Tolerance Margins (APK NL & BE)
European legislation sets strict limits on rolling circumference deviation to ensure the accurate operation of speedometers and safety systems (ABS, ESP, Traction Control):
Netherlands (RDW APK Standard)
The rolling circumference may officially be at most 2% smaller and at most 1.5% larger than the original factory size. With a greater deviation the speedometer will indicate a lower value than your actual speed, which is prohibited by law.
Belgium (GOCA Vehicle Inspection)
In Belgium, the inspection strictly refers to the Certificate of Conformity (COC). The tolerance on rolling circumference is set at -2% to +1.5%. If the chosen tyre size falls outside this margin, the vehicle will fail the inspection.
Recommended Tyre Brands at Wheels 'N Customs:
Michelin: Pilot Sport 5 & Pilot Sport 4S (UHP)
Continental: SportContact 7 & PremiumContact 7
Hankook: Ventus S1 evo3 & i*cept winter tyres
Pirelli: P Zero & Cinturato P7 with rim protection
Nankang: AR-1 & NS-2R semi-slicks for track use
Falken: Azenis FK520 & Ziex ZE310 ecorun
Professional Tyre & Wheel Fitting in Nijkerk
Unsure which tyre size fits your new wheels without rubbing or speedometer error? In our Nijkerk workshop we provide expert test fitting, scratch-free mounting of tyres on wheels, precision balancing and TPMS sensor programming.
Our fitment specialists are happy to calculate the exact sizes, ET values and widths for your car.
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