Try and keep it around the 150 mark.
I carry a minimum of 3 rifles and a shotgun at all times though so it's higher than it needs to be
Another tip for reducing weight is to regularly clear down your grenades and mines. Like aid this needs to be kept on top off if you pick up every grenade and mine you see like I do, I generally store a ton at my workshop so I'm just carrying 10 grenades and a couple of powerful mines.
Stealth boys are another ting that can quickly get out of hand if you don't keep an eye on it, they weigh 1 each and you can quickly be carrying 15-20 of them if you are not careful.