In one episode of the first season, Kenny partnered Max, Tyson, Ray, and Kai according to age (episode 42, "Fortunes Dear and Dire"). This apparently showed that Max was the youngest, followed by Tyson, then Ray, and finally Kai. Hilary's exact quote is "For instance, that book says the youngest player should team up with the oldest player, that means Kai and Max should be partners".
However, the second Beyblade DVD contains character bios which state that all the Bladebreakers except for Kenny are 13 years old (if you can get a picture of this, please contact me). Why does this matter? Because I'm told that originally, Kai and Tyson were both 12, but then Tyson had a birthday and turned 13, making him older then Kai. And thus, this would create a conflict with the above stated ordering of ages.
Assuming they are both 12 to start with, if both Kai and Tyson had their birthdays sometime before or during the episodes shown on the 2nd DVD, then they could both be 13 years old as the 2nd DVD bios states.
Of course, I'm also told that Ray is the oldest among them, and Max is older then Kai, but he's also younger than Tyson. This would make Ray the oldest, followed by Tyson, then Max, and finally Kai.
So who is right? What is the proper age order? If you can provide hard evidence from official sources regarding the ages of these characters, please contact me.