you can't get a 38 on a 6 bolt hub and there are bigger sprockets for the front "off the shelf" than a 15
i ran 17/39 20" tire and went 107mph but the calculator said it should have been more for my rpm's.
regardless you're going to need 80+hp and a 17/38 sprocket setup, at least a 10,000 rpm motor. that is if you wanna reach 110 in, or under the 1/4 mile mark.