Larry, I think this is how it works. I'm using * for multiplication and / for division.
driven pulley speed = motor speed * (motor pulley circumference / driven pulley circumference)
Note that circumference is linear with respect to either diameter or radius, so either of these measurements may be substituted for circumference as long as you're using the same measure for both pulleys.
To go from rpm to fpm on a bandsaw we remember that the bandsaw wheel rpm is equal to the driven pulley rpm since it is a one piece construction.
bandsaw fpm = driven pulley speed (rpm) * bandsaw wheel circumference
In this calculation circumference
must be used, as the circumference is the translation between rotational speed to linear speed by definition.
A quick reminder:
circumference = pi * 2 * radius = pi * diameter
So, for your saw:
driven pulley speed = 1725 rpm * 2.5 / 6.5 = 663 rpm
circumference = 3.14 * 1 = 3.14 (12" is 1 foot even in MI, right?
)
bandsaw fpm = 663 * 3.14 = 2084 which seems slow (I used many more decimal places for pi and the driven motor speed, so if you come up with 2082 or 2083 fpm just accept this as rounding error) for hardwoods. If Larry mistyped and meant he had a 14" bandsaw his fpm would be 2430. If Larry has had too many beers already and meant he had a 17" saw the fpm would be 2951, about right for hardwoods.
I hope this helps and that I didn't screw up my physics or math.