[1speedbike]

If you have a lower tire pressure, more of the tire is in contact with the ground. At higher speeds this could cause a lot of friction and therefore a lot of heat to build up in the tires, which can cause them to fail. Also your treadwear is gonna go to shit. I think that's why they recommend running higher pressures when driving faster. If you don't spend an appreciable bulk of your tire over 100 MPH, like on an autobahn, then you don't need to worry, as not enough heat will build up in the relatively shorter amount of time. If you spend a decent amount of time on a highway that will allow for 100 MPH or over, you can set them somewhere in between to be safer. I don't think tire pressures that high are good for highway driving. I've driven on snow tires at 100 MPH at about 38/38 and had no problems (though for the 135i the recommended pressure is 36/36).