Given the large number of variables whose exact values are not accurately known, any prediction of MPH versus RPM can only be approximate. That said, the Excel spreadsheet linked below allows the user to enter tire size and axle and gear ratio data and then view a chart of MPH versus RPM.
Remember that the third digit of most of the input data is a joke, and even the second digit is often suspect (do you really know if your tire's section width is 225 mm?). Thus, treat the resulting graph with suspicion.
To download the zipped Excel spreadsheet, RIGHT-click on the link below and choose "Save Link As" or "Save Target As" (depending on your browser).
Unzip it, open it in Excel and have fun!
Some browsers let you manipulate the spreadsheet directly in the browser window:
Bonus! Horsepower required to reach given top speeds. Accounts for drive train friction, frontal area, drag coefficient, transmission losses, etc.
And the live, un-zipped version: