Hi, had a quick search but sorry if you know this: Carry a pressure gauge in the car!! I've just driven 50 miles at 50 MPH because the runflat puncture warning light came on in the middle of a thunderstorm (very, very wet motorway). Got home and found all the tyre pressures were OK (doh!). I think that the one of the wheels either spun or aquaplaned for long enough to set off the wheel speed sensor that triggers the warning. I guess this could happen on any slippery surface or if the wheels spin through over enthusiasm. I'm off to get a pressure gauge so that I can check next time. Hope that this may save someone else a boring drive home with everything on the road passing you.