I don't think any rapper could run sub 1:55 (unless there is one who was recently a track runner?) But sub 2:30 is NOT VERY HARD for some of these guys who are in great physical condition.
AND YES, 50 Cent COULD RUN SUB 2:30 back when he lost like 50 pounds for the movie role.
Want to guess how he lost so much weight besides liquid dieting? He ran like 3x a day on the tread mill. Do the math.
Sub2:30 is very hard without decent aerobic conditioning. 50cent in good shape MIGHT be able to run a 65-70something second 400m, after that I think he'd struggle bigtime. Let's be real -> tHE 800m aerobic component would prevent any of these rappers from breaking 2:30 without some regular treadmill running. It doesnt matter how tough you appear/are or how much RedBull and Vitamin water you drink, you MAY..(and that's a big IF) be able to sprint a 60-64sec 400m but 800m is a different story.