Assuming directional tires here...
If both rears are currently rotating backwards, then yes, you simply switch the wheels side-to-side on the car. Easy DIY fix.
However, if only one tire is running backwards but the other side is pointed correct, then the incorrect-rotation tire will need to be dismounted, flipped on the wheel, and remounted/balanced by a tire shop.
Tire shops generally know sets of tires have to be mirror-mounted on the wheels to achieve correct rotation orientation once the car....Once directional tires are mounted on the wheels, there becomes a defined "right" and "left". You obviously need one of each. If only one is off, they mounted both tires in a "left" configuration, for example.
But if both sides are currently wrong, then the wheels were just bolted on the car wrong, something you can fix yourself at home.
