max attribute points on armor?

What is the maximum number of points I can have on my armor for an attribute? For example, I can purchase a helm with primary attribute (+1), and apply a rune of superior primary attribute (+3), which equals +4 on my primary attribute. Is this the max, or can I apply more? Thanks.

Yes, +4 is the max for one attribute. But you can also get temporary attribute boosts from skills like Glyph of Elemental Power, Awaken The Blood, Expert's Dexterity etc. And you can find weapon mods that increase an attribute by 1, but with a 20% chance. There are also consumables like Golden Eggs, Candy Corn, and Grails of Might that give these effects for a few minutes.

You can see a more detailed list on the wiki:
http://wiki.guildwars.com/wiki/Attri...ing_attributes