I believe gear ratios are based on a 25'' tires.
3.73 , tire are 235-60-14=25.10=3.72
Some say they're based on factory sizes which would put me at 3.56 or 3.70 gear if going off the original 185-75-13=23.93 or 24.93 if going off 14'' tires.
If you have a 245-60-15=26.57 tire, you'll wanna run 3.91's to get a 3.68 gear at the ground.
Add 29'' slicks to that like me and the ratio is 3.23'ish which is why I'm building a set of 4.30's=3.72 maybe even 4.57's=3.96 at the ground.