This sounds like super useful info. I'm still trying to download from MEGA the 9gb vida file, may take all night at the rate its going. I can't understand why this is such ass backward affair. One would think someone would produce a total working unit and make a killing selling hardware and software...

i have these and love them with the pegasus rims

The higher the speed, the more the speedometer will be off https://tiresize.com/speedometer-calibration/

But a taller side wall will always give better comfort on a 17in wheel..

If you go with a different Aspect Ratio and don't want to throw off your speed indicator and odometer. You will need to go with a smaller wheel and/or a narrower tire. For example: With 225/ 50 R17 your speed and distance would be 3.5% higher then indicated. With 225/ 55 R17 your speed and distance ...

Wanted to add that usually - not sure if everywhere around the world, the factory tire size specification is to be found behind the gas filling door. That tire dimension (including the tire wall size) has been used to calibrate the car speedometer.

I'd stick to 50 profile at most to keep reasonably within specs for circumference.