Do i need a rear camber kit?
 

tires are wearing very bad on the inside. My friend says i need a tow adjustment... :/

Yeah, you've got too much negative camber. A rear camber kit (arms and toe bolts) will allow you to bring the camber closer to spec and reduce the excessive inside camber wear (on new tires).

My rear camber was 2.9 after installing springs and at 9K miles I had steel cords showing on the inside of both rear tires. I added the toe bolts and now my alignment is back within specs on the rear. I hope the new set of tires last a bit longer.

IMO, rear camber arms and toe bolts are needed.

You can't really say for sure whether it is camber/toe or both. Camber will put more pressure on the inside of the tire but technically your tire could look like that after a few years with a lot of negative camber... if your toe is off it technically could look like that in a much shorter amount of time as the inside of the tire "feathers".

One thing is certain, you need a camber/toe kit regardless.

its been lowered for about a month 1/2 and this is the result :(