Is it normal that i don't trust my friends?

Totally normal! If by "don't trust" you mean they may deceive you, lie or borrow without asking, maybe even sleep with your ex or next, then it is normal to feel this way if you KNOW your friends. Hypothetically speaking suppose your friends are the proverbial, "Hoochie Bomb Squad," and you know they were known for sleeping with married men or lying, or even just taking your things without borrowing. You can only trust them to be them! Remember that! Birds of a feather do not always flock together. So you don't have to run out and befriend saints. You know and love them flaws and all so you can't trust one with your clothes and another around your boy toy. It is only right that you feel this way about them and if you can't take the good and the bad then move on but remember even in friendship you can't help who you love.

You should trust your friends but not too much, otherwise they might take advantage of you.

all your friends? some i trust, some i don't as much. depends on their reliability i guess

@theLlidD thanks for your comment, all my friends talk really bad about each other behind their backs

You may not trust strange people, or strange people in groups. Familiarity creates ease, you can perceive and judge more safely someone or groups you know. Say how downtown Chicago on a Tuesday is predictable, but Istanbul during a bombing raid might be a little more chaotic.

You may not trust some one you just met, or a friend of a friend.

Friendships are built on a relationship of trust.

Example:
Two Friends break onto a roof top of an apartment (they trust each other not to rat on another) So a gust of wind knocks one off - and they other runs to the edge and catches his him with his good.

He says, "Do you Trust me?"

So after he saves the guy he asks, well did you trust me? A friend would say "Heck no man, I thought I was a goner'" (Because he trusts that they can joke about it)