String setup Front and Rear Different OD.

When the front and rear hub height is different, in the case of either different OD tires or different sized wheels. Do you still set the strings to pass through the center of the front and rear hubs or should you try to get the string parallel to the car / floor?

Hi James, good question. I think either approach is an option, but there are errors no matter which way you choose. My perspective on this is that you should make the string parallel to the ground plane. Choose a string height somewhere between the two axle heights. Unless the difference in rolling radius is massive then the measurement difference will be negligible 🤝

Thanks for the tip. Front and rear OD difference is about 1inch (26mm) so about 1/2 inch (13mm) in difference.

For this difference, it will not cause you any issues. Good luck!

The technical term for this is "cosine error". As Tim said, it is going to be a rather small variance if doing a toe setting, either way.

Personally, as all the measurements are either taken in reference to the plane of the ground, or perpendicular to it, I would run the string on the same plane.