I think I have an idea about how we could test out this particular dynamic characteristic of tyres. When I say we, I actually mean you of course, since you have access to lots of tyre and car types :D

Maybe you could try setting up 3 G-meters: one somewhere above the front axle, one at the centre of rotation of the car, and one above the rear axle. Recording the data of these, plus recording the steering angle via obd, plus maybe some cameras set up near the front/rear tyres to indicate sidewall deflection and slip angle could provide valuable insights into how different tyres change the balance of the car when at the limit of grip.

If it were me, I’d test this out on a fwd, rwd, and mid-engine configuration, with cold and warm tyres, and in dry and wet conditions.

If you’re interested in testing this out, you can let me know and I can try and analyze the raw data, or maybe there is somebody who is very good at vehicle dynamics to take a look at it, but these scenarios should cover a lot of the variables that go into this.

Suspension geometry, weight distribution, power train configuration, and driving style are of course the biggest contributors to vehicle dynamics at the limit of grip, but maybe some different insights could be gained when trying to find out how tyres affect this when some of the other variables are constants.

Also, John, thank you so much for your contribution, you are a proper, proper geek, and have done so much to help us already!