"I've decided to get rid of my run-flat tires that came as Original Equipment on my 2009 BMW 335i Coupe Sport Package and make the switch to non-run-flats. I've heard that I should use higher air pressure, is this true? If so, what tire pressure do you recommend?"
As a moderator of several BMW forums, this is a question I receive often. Switching from run-flats to non-run-flat tires has become more common for BMW drivers.
When changing to a non-run-flat tire, some drivers feel the tires may appear to be underinflated, when in fact, they are not. While you could add more pressure to correct this appearance, this often causes more rapid tread wear in the center portion of the tire. Because of this, we recommend using the same inflation pressure, even when going to non-run-flat tires.
The vehicle manufacturer's recommended tire inflation pressures have a lot to do with load capacity, handling and a variety of other factors. Vehicle manufacturers, in particular BMW, take the time and effort to tune and test before recommending inflation pressures based on how the vehicle is being loaded and driven. We also strongly discourage going lower than what is recommended by the vehicle manufacturer.
Depending on what year your car was manufactured, the doorjamb placard or owner's manual may show only one inflation pressure recommendation to keep things simple. Usually, the OEM defaults to the worst case scenario of fully loaded and higher speed use, which puts a pretty high psi recommendation on the placard. From a tire durability standpoint, it's better to be 5 psi over than 1 psi under. Therefore, erring to the high side makes some sense, even if not ideal for the way many drivers actually use the vehicle.
Remember that the pressure listed on the sidewall is a maximum pressure only, not a recommended pressure. Instead, use the air pressure recommended in the vehicle's owner's manual or tire information on the placard label. The placard is typically found on the driver's side doorjamb (like the example in the photo above). For more information about recommended inflation pressures, read "What Air Pressure Should I Use in My Tires?"
If you're still unsure about whether or not to change your tires from run-flats to non-run-flats, check out "Ditching Your Run-Flat Tires for Non-Run-Flat Tires on Your BMW? Read This First!"