I assumed he had a TF, so ratios are 2.45-1.45-1.00.
MPH= (rpm x Td x 3.1416)/1056 x R1 x R2 = not rocket science. Had you had your thinking-cap on you could have figured this out in just a few seconds.
(5000 x 27 x 3.1416)/ (1056 x 3.55 x 2.45) = 46.177mph@ zero slip
(6600 x 27 x 3.1416)/(1056 x 3.55 x 2.45) = 61ish @ zero slip
Post #5 edited to clarify.
