Changing your wheel size does NOT ALWAYS mean you need to recalibrate your taximeter. It depends which size tyres you use.
Changing the diameter of the tyre DOES always require a new taximeter calibration.
The taximeter will not calculate the journey price correctly if not correctly calibrated.
How to calculate the tyre diameter (D).

- A =Tyre width
- B= Tyre wall height
- C= Wheel size
- D= Diameter

Find similar numbers on your tyre.
A=225mm. Change this to inches
225 divided by 25.4 = 8.86inches
50 is the ratio between tyre width and height
B= 8.86x 0.50 = 4.43inches
C= 17 inches
(D) Diameter= B+C+B
D= 4.43+ 17 +4.43 = 25.86 inches
Compare the diameters between old and new tyres
If there is a significant difference, you need to recalibrate the taximeter.
You may find this link from another website useful.