Relative rotation wheel to x translation with script. How to find the radius of a wheel?

Hello all. I am trying to rotate a wheel by taking the x position of the vehicle in the scene.
I took the x translation and run it through this expression:

(value(column(“Car-P_Pos_x”)) / (23,140.15)) * -57.2958;

My problem is that I cannot figure out the radius of the wheel. In my case it’s the 0.15 which I found it by experimenting different numbers until I got it to feel right.
Is there a way to find the radius of a circle? Is my process wrong and there is another way to make the wheel work without experimenting in different numbers on the radius?

Thank you very much in advance.

p.s. Here is the example I am working on. The front wheel is rotating by the script.