I’ve been debating 4.56 vs 4.88 for a long time. Doing every calculation possible from 1st-OD at different speeds, and comparing to stock 4.56 makes more sense. 35s are my max, I might go down to a 34 or back down to a 33. I prefer running smaller tires (245 or 265s) in the winter as well.
The ratios in the A340F trans are 2.804, 1.531, 1, and 0.705.
Stock gears are 3.909 with 265/70/16 (30.6), rpm at 100km/h = 1891 , at 120km/h = 2270
3rd gear at 120km/h 3219 rpm
4.56 gears 4.555 with 315/75/16 (34.6), rpm at 100km/h = 1949 , at 120 km/h = 2339
3rd gear at 120 km/h 3318 rpm
So even with 315s I’ll be slightly over geared
If I run 34s at 100km/h = 2019 rpm
4.88s are just too low in my opinion. If I was v6 4.88 100%, but with the shift kit/valve body mods I can climb hills at 85 km/h with 33s and stock gears at 1500rpm. Shift kit really changes the way your transmission responds, torque converter stays locked up longer, quicker firmer shifts, awesome downshifts, higher line pressure, just makes everything better and better fuel economy.
I also like the extra tooth on the pinion, 9 vs 8, so my mind is made up 4.56.