I was driving when I began smelling a burning, possibly rubber, smell and when I pulled over there was smoke coming from my passenger side rear tire well. Nothing appears to be wrong with the tire or anything out of place, but I did just pick it up from a lot where it was towed. Any suggestions on what could be going on? Thanks!
If your tire was burning you'd know it, and it wouldn't stop when you stop the car. If you have a rear wheel drive car then it could be from the drivetrain, but I would bet it's the parking brake. Parking brakes usually work on the rear wheels, either with a separate set of calipers and pads, or by clamping the main brakes. It could also be a stuck brake caliper on just that side as well.
Either way you have have caused significant wear to your brake pads, possibly making them need replacement. It could also have damaged your brake rotors by wearing them down, warping them, or both.
You should really get your car to a mechanic.