Air for the tires

I have two tires on my van with a slow leak. I have yet to make the hour and a half drive to go get them fixed so occasionally I have to go put some air in them. My car has this cool feature (maybe most cars do now, I don't know) where it shows me on the screen on the dashboard what the tire pressure is of each tire. It will alert you when one is low, or two. On our way home the other day I stopped at the gas station to put some air in them so I wouldn't have to the next morning since they were starting to get low. On a side note, I think it's ridiculous that we have to pay 75 cents for AIR. That's dumb. Nate was getting tired and hungry and a little weepy, so I brightened his day by asking him to come up to the front seat and yell out the window to me when the numbers changed since I don't know how to read the gage that comes on the air hose (after this experience I now do know how to read it). With the first tire I told him to tell me when it got to 35 or higher. So after what seemed like forever he finally yelled out the window 3-6. So I put the cap back on and started to walk to the other tire, glancing in the window at the screen as I walked by. It said 63!!! Which I probably wouldn't have freaked about except while I was sitting there forever blowing up the tire I read on the tire that it said to not go over 40. And then later when telling Jason about it he informed me that the tire could have blown up in my face!!! So by the time I had let enough air out of the tire, I had ran out of time and had to pay another 75 cents. So new plan for the second tire. When the tire is low it highlights it in yellow, so I told Nate to tell me when it turns from yellow to blue, thinking I'm really smart. So after a little while, but not nearly as long as the first time he yells out the window that it's blue. I put the cap on and walked over to put the hose away, as I glanced in the window again. This time it said 56! Augh! Apparently he wasn't watching and didn't really noticed when it changed colors. So again had to let a bunch of air out. Luckily, neither tire blew up in my face and it all ended well. But I learned my lesson =)