2008 Mercedes CLS-Class Owner's Manual - Page 304

Operation Tires and wheels Tire inflation pressure changes by approximately 1.5 psi (0.1 bar) per 18°F (10°C) of air temperature change. Keep this in mind when checking tire inflation pressure where the temperature is different from the outside temperature. Checking tire inflation pressure Warning! Regularly check your tire inflation pressure at least once a month. Check and adjust the tire inflation pressure when the tires are cold. The tires can be considered cold if the vehicle has been parked for at least 3 hours or driven less than 1 mile (1.6 km). If you check the tire inflation pressure when the tires are warm (the vehicle has been driven for several miles or sitting less than 3 hours), the reading will be approximately 4 psi (0.3 bar) higher than the cold reading. This is normal. Do not let air out to match the specified cold tire inflation pressure. Otherwise, the tire will be underinflated. Follow recommended tire inflation pressures. Do not underinflate tires. Underinflated tires wear excessively and/or unevenly, adversely affect handling and fuel economy, and are more likely to fail from being overheated. Do not overinflate tires. Overinflated tires can adversely affect handling and ride comfort, wear unevenly, increase stopping distance, and result in sudden deflation (blowout) because they are more likely to become punctured or damaged by road debris, potholes etc. Do not overload the tires by exceeding the specified total load limit as indicated on the Tire and Loading Information placard on the driver's door B-pillar. Overloading the tires can overheat them, possibly causing a blowout. Overloading the tires can also result in handling or steering problems, or brake failure. G 303