What causes bad grinding noise in rear with new pad driver side tire leans in

First and most importantly > Make sure wheel lugs are tight!! ..

Hello, yes definitely make sure those wheel lugs are tight. Aside from that, nothing touched when replacing brake pads will create a situation where the tire/wheel leans inwards at the top. It could be that you're noticing something that is as it was before the service was performed. As far as the "bad grinding sound", for this I would definitely check the installation to ensure the pads were installed properly and that any shims and/or anti-rattle clips are positioned correctly. Additionally, if the brake rotors were not resurfaced when replacing the brake pads, a noise could result from the new pads verses the old mating surface. The brake rotor surface could have hot spots, rust pits...too hard to tell over a computer! But I would definitely have a good look.