brake ducts can be a bit tricky. one thing a lot of new players to AMS2 do is think they are over heating because they shoot up really fast when you brake, but of course they go back down fast too. so lets say you brake, it shoots up to red for a moment but that is not really a big deal, the trick is to see where the temp is before you start braking. THIS IS NOT CANON so dont quote me on this but..anything around or below 350 when you start into a brake zone should be good, even a bit more. it is once you start having a starting brake temp of 400 that you may have problems..and be careful some tracks can have a slow build up of heat, like Imola, where every lap the brakes are just a bit hotter when you go into turn 1 and after 5 or 6 laps they may get so hot that it effects how you brake. If in you are worried about it you can go more toward the open side..50/40 will work on all tracks as far as i know at least with GT3..at Spa and tracks with long straights between braking zones you can go as low as you dare. of course one big off means the end of the race and unless you are at the razors edge with aliens i dont see the point in risking it.