There is a pic on this site of someones display showing, I think, 55d. IIRC it was a track day with better tires. I personally have not gone past 42d, but that's just me on public roads and I still have about 20mm of chicken strips left, so plenty of room for mistakes or corrections. I can't count how many times I've come through a turn to face a head-on vehicle that couldn't hold their lane, or a deer, or skunk, or squirrel, or bobcat or coyote, and so on.
Something else to consider is that the degree the turn is banked will greatly impact the lean angle you record. An off camber turn will see you run out of tire at smaller lean angles where a turn that is banked well can get you a really impressive number and not even hit the foot pegs.