ramps are fine, you need to use common sense like anything else. like dont use them on dirt or grass with out a board under them. or they sink and kill you.
dont use them on your driveway on a hot ass day as they will sink into the driveway and leave nice scars. always use a board under them on a drive way. cement is fine. asphalt will get f ed up
once they are bent, toss em out, buy a new pair.
the big one, always set the e brake while in gear, then put the car in neutral. let of the pedal brake let the car settle, then into park.
when its time to come off the ramps, put it in gear first, then take the e brake off. doing this will keep it from doing that god awe full clunk.
this is how you should also park on hill to keep from the park pawl getting hung on. provided your e brake works.
