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Another good way of testing a tyre is to hit the brakes hard and see not just how quick it stops but also how often the abs kicks in, the more it kicks in the less grip the tyres have.
I'm not sure that's a recommendation I would use to assess the overall ability of a tyre... how about lateral grip.
I have reasonably extensive experience of these tyres on a BMW 120d. They are more sensitive to temperature than almost any other road tyre I have experienced. With the BMW if it was cool, even on cool spring/autumn mornings, if you were not careful it was very easy to spin up the rears for the first few miles and the steering felt fairly wooden for longer. If it was warm or you got the tyres up to temperature there were no issues. In the wet, generating temperature, especially if it it cool/cold either never happens or takes a long time. Two likely suspects, firstly compound and secondly stiffness of the sidewalls. The sidewall stiffness effects the warmup because there is much less sidewall flex.
There is a potential positive, once warm the stiff sidewalls can give a more precise steering feel on ititial turn-in, tyres with softer side walls e.g. Goodyear Asymmetric (I'm not saying that these are bad tyres but have a different construction) to me tend to feel a little less precise on initial turn in... Of course, the downside of this on a front wheel drive car would be the lack of temperature in the rears.
Back to the Bridgestones, they are at least adequate and better than reasonable in warm weather. I'm sure that, if I bought a new car with them on, I wouldn't go out immediately and replace them but I would change to something with a wider operating range when the time to change them came along. In the meantime I would learn their limitations and attempt to dive accordingly...
I have a Jaguar 5.0 XKR with Michelin Pilot SuperSports all round... widely regarded as a very good tyre... but for the first few miles - until they have a bit of temperature - if you're not careful... the rears will spin up with (including lots of popping and banging as the traction control cuts in) only light application of the throttle... I just (try) drive accordingly...