Someone tell Stu to clear his inbox. Also, tell him:
Hey! File tread will be fine regardless of rain or not. The sticky clay might suck a bit more, but it'll suck with any tire, and there's very little of it considering the length of the ride. Volume trumps knobs IME.
Gas stations - there's a long ways to the first one at mile 47 in Chester. Then you'll have an aid stop and several stores in Eastman (mile 65) and then there's a Chevron when you cross I-16 at mile 100, and then it's 24 miles to the finish line.