Are you doing the endurance in A-spec or B-spec? AT or MT? The best gear setup depends a lot on who's driving, because an extremely long gear setup can force B-spec to keep the car in low-RPM's around corners, thereby reducing fuel consumption and tyre wear, even when set to pace 4. This also applies if you're driving in AT. MT drivers can run much more optimal gear setups, as they can avoid dropping to 1st gear and keep the car in 2nd gear and above at all times.
The 'gear trick' is basically the method used to get the closest gear ratios the game will allow (as in, the RPM drop between each gears is as small as possible). How it works is, you move final all the way to the right, set the auto slider to 1, then move the final gear left again. Doing this resets the ratio ranges so the ratios are as close as possible.
However, the trick is only half of what you need to do for the best gear setups. Especially for FR's, you'll need to arrange the sliders so 1st and/or 2nd gear are towards the left, and 4th/5th/6th gear are towards the right, so the RPM drops are even smaller than the default arrangement. Usually you'll want to set up your gears to look like this:
However, if you're driving in MT and want even closer gears, you can also run this pattern, then ignore 1st gear while driving:
I did a
TT-R Touring Car tune a few months ago, though it uses the stage 4 turbo so it can compete in GTWC/Extreme League events. For Nur 24hr, you probably don't need a turbo at all. The gear setup I used was: final to 5.000, then auto to 1, then final to 2.200, then set individual gears to 2.779, 2.210, 1.770, 1.433, 1.163, 0.987. You'd probably want to run a shorter final though so the car doesn't get bogged down at low-RPM's constantly.
