[header] How to use car ramps [title] Check the maximum rated load. [step] This is the most important characteristic of your ramp: the larger this number, the safer you'll be. The ramp's rating refers to the maximum gross vehicle weight (gvw) that can be driven onto the ramp. 
You can find the gvw on your driver's door sticker or owner's manual. The ramp's rating should be well above your car's gvw, to allow for a margin of error or a front-heavy car.