and also to add on to those that say 1 att/str, wow. you can get 70 att & str without affecting your combat, and that would OBV come in handy when training your def to 99, unless you feel like halving both your ranged and def exp in order to train the two in which i'd wish you good luck hah.
i recommend being a p2p tank, and also, don't go straight for maxing, get a nice 40 def 85 - 90 ranged 'rune ranger' first, because they're good for the lower levels and you have everything like veng etc. and when your tired of getting hit a lot/getting fun kills get your def up to move up in the ranks.
gl on it though, tanks are an investment of time, even if your botting it.