lets get through your temp/overheating variables as well - a 155 won't have the same grip as a 195 when its dead cold launching from a standing start, or in the first couple of laps before its overheated, or in a short squirt through a couple of corners during general street driving (where tyres don't get excessively hot).

As I said, my example of the wider tyre was on the rear, so there is no scrub radius consideration! All I changed was the tyre width, not the wheel, so no change in track or offset which is why I didn't mention them.

I have data that shows I was generating a fairly consistent 0.1-0.15 more G with the wider rear tyres on because instead of braking traction with the rear end, they just keep on gripping. You can throw in as many inapplicable variables as you want and theories as to why wider tyres don't offer more grip, but you'll have a dickens of a time convincing my accellerometer and timing system that wider tyres don't grip better.