Yeah for me they should test using all 3 main configs FF FR 4wd would give a more complete overview of what the rubber can or can't do.
I think its more complicated than that , I reckon vehicle weight is a huge factor as well but ultimately its down to how the driver feels and that is entirely subjective , anyone who gets to the limit of their tyres regularly on the public road is probably doing something wrong
Absolutely agree with this. There are so many external factors that can affect the performance of the tyres (without actually being related to the tyres themselves); the weather conditions, how you are driving the car, mud on the road etc.
Like Rich says, if your tyres are surprising you then you need to lighten your boot.