I'm in the middle of work right now, I drive for a living and after pulling out of a store I all of a sudden heard this strange grinding noise that seems to come and go as the tire turns. This is so far at low speeds and seems to go away for the most part when I turn or hit the brakes. What could this be? I can't tell if it is the front or rear tire so far as I am alone. Can I get through the rest of the day, I'd say I have another 100 miles to go.