Tweaker Tyre and Helmet Positions

I'm creating a fantasy carset with a mix of different cars from different years from different CSM mods. All good so far but in game I just can't get the tyre and helmet positions right. I don't know what these should be. I've tried copying them from the CSM mod that I got each car from, but even then they don't seem to match and I end up with a helmet inside the airbox and tyres half on the brakes.

Can someone explain to me simply where I get the numbers from?

I've tried searching on here and googling but whilst theres lots of threads around this subject, none of them seem to be able to tell me what I need to know.

Maybe you have to match tweak positions by driver in GP Tweaker... that’s what I do, and goes okay

Paulo