Keeping autoincrement ID 2 digits. Possible?

Hi there, I am wondering if it would be possible to have a autoincrement field which is only 2 digits long. The idea is, that as soon as 99 is reached the next value will be a free one withing 0-99. E.g. A forum has not more than 99 different forums. So lets say we will keep the ID 2 digits. Forums can be deleted and created by the admin. As soon as one is deleted, there is an empty number. E.g. 5 So we reach 99 and the next number should be not 100 but 5! I did set the type of the field to int(2), but it does not change anything. Still 100. Has anybody a good idea? Thanx Andy PS: if somebody is wondering why 2 digits... I am passing this value like that : viewforum/01.html