I don't think it will be a problem as street tyres only tend to go greasy when pushed hard on a racetrack and exceed their designed optimum working temperature.
As they can work well within their operating range at the tyre warmers' preset 80?? maximum along with the fact that they'll only get cooler at this time of year as there's no way anyone (not even Ben) will be able to maintain the heat in them, I can't see there being a problem other than the obvious reduction in grip as the tyres cool off.
I think it will be interesting to see how Ben gets on with it and if he finds the reduction in grip a weird thing to deal with. I know in the past a few magazines have used tyre warmers to get cover shots in crap conditions without any problems, so best of luck to him!
Posted: 10/12/2009 at 16:37