As it stands, if you read a +6 Int tome, right before TRing, you would get expanding effects as you level. At level 3, since it's the first level you could use a tome, it is treated as a +1 tome. At level 7, it jumps up to a +2 tome, etc., until you get up to whatever level you need for a +6 tome to take effect (23?). How about making it so normal tomes can grow with you too. Read a +3 tome at level 7, and you get an immediate +2 bonus, that becomes the full +3 at level 11 (the first level where you could have taken a +3 tome).