MOD 1 pinion question

[BrianG]

The problem you are having is the high diff ratio of 4.09:1 and the largish spur of 48T. To get a lower rollout ratio with those values for the speed you're looking for, you're gonna need a large pinion. And since you are looking for a real 60mph speed, you should probably be shooting for a calculated speed between 65 and 70 mph, because wind resistance will drag you down a bit.

FYI, when you enter tire size, use the entire tire diameter, not just the rim.

What vehicle is this in?