We are using the same formula. If you plug in your numbers

New Tire / old Tire * gear ratio = new gear
33 / 27 * 3.07 = 3.752

The difference is I am saying the stock tire P235/75R15 has a diameter of 28.9 inches, and the typical diameter of a 33 tire is more like 32.8 inches, so:
32.8 / 28.9 * 3.07 = 3.48

We are using the exact same math, just starting with different numbers.
So for 35s:
34.8 / 28.9 * 3.07 = 3.7

This means the 3.73:1 gear ratio would get me back to stock with 35 inch tires. I have 33 inch tires so I am over gearing a little.

I know that at 69MPH (using GPS) I am currently at 2200 RPM,using similar math, with 4.11 I will be just over 2900 RPM and with 3.73 gears I wil be around 2600 RPM at 69MPH.