@J.R. and @xman
I don’t know how else to explain it, but I’ll give it a try with a simple example:
Hopefully everyone agrees that given the same conditions and speed, a car of a fixed mass generates a set amount of lateral force when taking a corner or bend in the road? When tyres with the same amount of grip are fitted, this force is distributed (relatively) evenly and the work is split. In this scenario, when the car starts to lose traction, the mass is distributed anywhere from 60/40 up to 50/50, front to rear for most modern cars. With the outer tyres doing more of the work obviously.
When tyres of mixed capabilities are fitted, this same force is distributed unevenly at the point of losing grip. What was previously a relatively even share of the work has changed because the tyre with superior grip is nowhere near losing traction. The tyre(s) with lower (weaker) grip now has to deal with more mass and loses traction faster than it would do previously. A sort of pendulum effect.
Bumps, potholes, and spillages on the road can further exacerbate the issue. You guys are obviously experienced, well above average drivers so this only applies to other road users. When I mention mixed capabilities, I’m referring to winter or all-season tyres mixed with summer tyres. Apologies for using industry accepted “summer” terminology. A full set of “summer” tyres is safer than mixing winter or all-season tyres with summer tyres during winter conditions IMO. I’m more than happy for someone to actually explain why they think this is wrong, or I suppose you can just call it “nonsense” and “tosh” again.
As I said before, it’s probably best that we just agree to differ, especially as one of you seem to think winter tyres, or their benefits, are a myth.