What are the levels for item tiers?

I want to start self-cubing my equips, but I'm not sure if I'd have to upgrade some of equips to get to higher tiers. What are the level ranges for the item tiers, and what's the max % you can get on them? :C

Level 0-30 Tier 1
Level 31-70 Tier 2
Level 71+ Tier 3

I dont know the exact %s for each though/.

http://www.southperry.net/showthread.php?t=52772

For all probability info.

Ooh, thank you~. c: