This is a normal, if not frustrating thing. Air will slowly seep out of the tires and will have to be topped off once a month to keep them in the optimum pressure range to get the best mileage and performance. One way to help with this is to have your tires filled with nitrogen, most shops can do this for you today. The nitrogen molecule is larger than the air molecule so it stays in the tire longer, it will still need to be topped off just not as often.
#tire #air #nitrogen