Jax62812

I'm hoping someone could help me out with this. I planned on installing a spoiler with a brake light on it. I was thinking of tapping into the brake light harness, but unsure which one it would be? I believe it's the 4th on the setup which would be the "RED" wire. If someone could help me with that, I'd appreciate it so much. Or if someone has a better idea of a place I could wire into.

Thank you guys. It's truly appreciated.

Looking for opinions or answers. I Currently have 215/50R17 95V Tires and stock wheels with stock height on my 2013 Legacy. I was wondering if 235/45/18 OR 245/40/18 would fit without me having to change anything on the car for these to work? Any help would be appreciated.