Thought I would keep the discussion about tractor operation on hills going on a bit longer.
There's an iPhone App that's a
clinometer, used to measure % and degrees of slope--it yells at you too

Turns out a couple places on the woods trail/road are around 20 degrees, which is almost a 39% slope. When I graded these I made sure at least there is no "tilt" side-to-side, but it's a tad steep. I may be able to improve this a bit with the new tractor.
Was reading today and some Ag safety guy said always drive the tractor DOWN a steep slope and then go backwards UP the hill. Is that right? Tractor Mike says always keep more weight behind you when going down, then travel in reverse when going up. Any thoughts on that?
In this thread it also says
not to fill the rears more than around halfway to keep the center of gravity low. Dealer says they fill them 90%. Thoughts?
For box-blading on steep, better to remove the FEL and put on suitcase weights?
So I did go one size bigger.
Specs that may relate to stability on hills:
Max26XL HST 4WD 25.6 HP
Bare Tractor Weight: 1863 (before filling tires)
Length: 109
Width: 54.3
Tires: R4, Front: 12 x 16.5, Rear: 23 x 8.5 - 12