Ok, so im not the most knowledgeable person, especially when it comes to tires and the cold...however I do know they flatten up a bit under cold weather. BUT my back right seems overly low and my car makes a thump noise when i first pull away (feels like its my back tire uneven with rest), and i dont have a pressure gauge to check the pressure as of right now, so i went and just put some extra air in to be safe, used the whole 3 mins worth. I then took a weekend trip up to my gf's college in jersey (2:45 up 2:45 back.) No problem with tires the whole time. Its now Wednesday and i went back out after class and saw my back right looking awfully low again. If there was a hole or slit wouldn't it have show by now? Is it normal for one tire to just look lower then another? I know i should check the pressure but i just wanted a quick answer for now.