Thumping in Rear

[CBod]

I have a 2010 Equinox that i put snow tires on last month and afterward when im making a sharp left hand turn i hear a thumping in the right rear. I put on a set of Goodyear Ultra-Grip Ice WRT tires. never heard this noise with my stock tires. to me it sounded like rust build up on the rotor hitting but ive machined them and cleaned the backing plates up so there is nothing hitting and noise is still there. It seems to get worse when there is a car full of people. Any one else have this issue or any idea what it could be