So I'm trying to learn some physics, calculus, and fluid dynamics on my own through research material.
I understand that the max speed and acceleration rate of a vehicle can be modified by changing the radius of the tire/wheel. I know that older cars that used a vehicle speed sensor on the transmission would read incorrect vehicle speed if you change to larger or smaller tires.
Now I'm curious.... If the 2003+ B6 uses the ABS wheel speed signal to display current speed on the cluster, would it be accurately accounting for wheel size difference and display the correct speed, or would it still fall short of accounting for the correct dynamic wheel radius.
Here is a small chart I made using a few samples of logged data of my B6 on 205/65R15 tires. The unloaded tire radius @ 35psi is 1.0622 feet. The loaded tire radius in the chart is listed as "Eff. R", but I don't know if that is a wrong number based on the car coming with the 17" with a different dynamic tire radius. Dynamic tire radius is the effective tire radius under load from the weight, and also expansion from high rotation speed.
Velocity Formula:
V = ( π * R * ( RPM / ( G¹ * G² ) ) / 30 * ( 1/5280 feet per mile ) * ( 3600/1 seconds per hour )
Radius Formula:
R = ( V * 30 / ( 1/5280 ) / ( RPM / ( G¹ * G² ) ) / 3600 / π
Where:
R = Dynamic tire radius in feet
V = Velocity in miles per hour
G¹ = Transmission gear ratio for 3rd gear ( 1.429 )
G² = Final drive ratio ( 3.889 )
