For a 2 stroke bike, If 1 gallon of fuel costs 3.50 and the oil you add to that one gallon costs another dollar, and that bike manages 100mpg average, it costs you .045 cents per mile just in fuel and oil.
Let's say your tires last 5000 miles and cost 60 bucks a set. .012 cents a mile. Let's not forget the tubes, call that 30 dollars a pair, bringing the cost of both together to .018cpm.
So, not including anything else, just the tires, fuel, and oil you are looking at .063cpm. If you wanted to just round all other wear and tear costs up in it, call it like 10 cents a mile.