Yes, the rainy season is upon us. Here in the Bay Area it is expected to be colder and wetter than normal due to the la Nina weather event.What that means is that you may want to check your tire pressures a bit more often, due to the fluctuations in the weather. Tire pressure drops because air just seeps through the tire on a regular basis, but the pressure also drops as the ambient temperature drop. Tire pressure loss is exacerbated by cooling trends, and the increase in condensation in the tire contributes to that loss also. It is always best to check your tire pressure in the morning before the car is driven;Why? Because after the car is driven, or in the afternoon, it can be easy to under inflate of 6 or 8 psi. Under inflation of your tires can be dangerous. The rubber is subject to “elastic hysteresis”. In layman terms that basically means the rubber can become misshapen under the load and speed of your BMW, your MINI or Mercedes, (or any car). The tragedies of under inflated tires and the SUV’s in the 1990’s sent a very strong message to the industry and the public of the importance of proper tire inflation. The tires became misshapen and basically came off of the wheels with catastrophic results.But, how often do you check your tire pressures? Optimum would be to check them once a week using a good ANSI grade “B” or above pressure gauge. The door pillar sticker will show the manufacturer recommendations for tire pressures based on the tires being “cold”, as in “not driven”. Keep in mind, that even driving a short distance will heat up the tire and affect the readings.Perhaps pick one day a week, before you begin your driving day and check those tire pressures. If you can get a regular schedule going that is great. Happy Motoring!