For about the last year, I've had a slow leak in one of my tires. I've had the truck in for oil changes and to have the tire checked 3 times. Once, the dealer changed the valve. This trip, the mechanic found a nail in the outer tread, about an inch and a half from the sidewall. The shop claimed that the tire couldn't be plugged. I'm positive that I've had tires with nails closer to the sidewall that have been plugged. Does the dealership claim that the tire can't be plugged sound correct, or does it sound like they want to sell a tire?