It really depends on how high they are....real low means less tilted...higher means more tilted...Play air drums and imagine the toms being where you want them to be...That should tell you how high...then tilt from there...Anyway that's my opinion..!!
Depends on how you play and your ability with finger control. I like floors flat and rack(s) nearly flat but just barely tilted. My racks are shallow though so I can set them low. Flatter angle gives me better stick response from the head. If you have deeper toms you gotta tilt em' unless you like to sit realllllyyyy high.