You step out into the driveway ready to start your morning commute only to discover a flat tire. How in the heck did that happen overnight? If the tire valve is missing its cap, the culprit might be a leaky valve. Those little caps keep out dirt and moisture that can cause leaks,
so be sure to keep caps on all your tire valves.
Another tip:
When you replace tires, remind the tire shop that you expect new valves with the tires.