From riding bikes for numerous years and tracking the car, I can't find an Arai helmet that fits my head well at all. I have a big head round head(so Im told), and find that Bell helmets work best for me. I use Shoei helmets when I ride, or use too I should say.
Just as everyone said, you really should try them on, its all about fit, not just for comfort but also for protection if you ever do get into an accident.
I also like a large eye port, but that a personal pref.
2008 AW/FR E90 M3-SOLD
2013 991 C4S