I have three tires that are consistently losing air in the cold weather. The soapy water trick didn't help. I replaced the Schrader valves yesterday. This morning one tire was down to 10 PSI but I found the valve was loose also. Probably my fault. Those things seem so delicate I didn't want to over tighten and mess it up. After work will be the test because my truck sits outside for 8 hours.