Last week I went to a gas station a block from the church to fill up. I didn't go to fill up my gas tank, I went to fill up my tires. I have had this Buick for about three months now but I had not yet put air in the tires. It turns out they were all under-inflated by about 10 lbs each. I was unclear however exactly what the tires SHOULD be inflated to. I couldn't find the information on the tire (besides, it was night and dark), and the sticker inside the driver's door that usually has this information was torn off.
So I put 32 PSI in each tire and drove off. It occurred to me later to check the owners manual. Oddly, the manual didn't say anything about the recommended tire pressure--except for one tire.
It said in big bold letters to be sure to keep the spare doughnut tire inflated to 60 PSI. I wasn't even sure where it was! The next day I found it hiding under the "floor" of my trunk and checked the pressure. The pressure was so low, it barely moved the needle on my gauge. Only to about 10 lbs.
So I took it back to the gas station with free air and after about five minutes of standing there pumping air in the tire, it is now completely inflated to 60 PSI. Hopefully I'll never have to take advantage of that.
My advice to you, again, 1) keep your regular tires inflated to the recommended spec. 2) find your spare (and I don't mean the one around your waste.) 3) inflate it completely. 4) pray that you'll never need it.
Would there be anything worse than having a flat tire on some highway, pulling over, jacking up the car, replacing the tire with the spare only to find out your spare is flat too? OK, there might be some things worse, but this is such an easy preventative fix!