The liability is probably in putting your car on a lift, not balancing your tires.
When I need new tires on my Spyder, I take the wheels off at home and take them separately. I'm currently getting an adapter made for my wide 5s so I can get them balanced. When that happens I'll do the same, and I'll be the one to remove the adapter and installing it on the next wheel. I'll use a rattle gun instead of their air gun set at max.