I've never gotten around to getting a tire pressure gauge for my road bike. How much of a gamble is this? I just look at the tire when I'm riding it, and if it looks low, I add air. I also pinch the tire and if it feels soft I add air until it is appropriately hard. This may sound foolhardy, but when I bought the bike and after they added the correct amount of air, I felt / pinched the tire and try to approximate that as a guide as to how the tires should feel. Am I the only one, or is this a risky, unreliable and unsafe practice?