First…
Do this only if you must.
Position the car so the side you want raised is on the low side of the slope.
I use ramps… (Just don’t trust jack stands on a slope.) Once the car is driven up onto the ramps… I chalk the rear wheels and place two of my spare wheels with tires mounted (one on top of the other) under the rear differential or the front cross-member, depending on which side your working under. They slide up under there with a minimal clearance or actually slightly wedge up into the car… making a potential death trap as safe as fort Knox.
PS I hope no one needs this tip.
