Have installed 17"mags from an XC90 on my V70XC with 225x65x17 tyres to allow for XC90 front brakes. Anyone know how to change/adjust components to get speedo reading a more accurate speed
Modifications to speedo to adjust for bigger wheels and tyres
Use phone or GPS unit to check where you are at first.
If you know the difference from that you can remember it or put thin strips of electrical tape on the speedo.
Maybe a tech whiz could get into your car's brain and change stuff via VIDA?

Have added a photo so members can see the why, Have already checked speedo with GPS about 4% slow.
Brakes are still std, next jobs fitting the bigger calipers and discs.
Downsize the tyres?
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There is a tyre circumference that's displayed on Vida when you scan a car probably, stored in the BCM or DIM.
Not sure how you can change it though probably would need a dealer to change it with new software.