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I hate getting curb rash on my wheels. I try to be careful but accidents happen and sometimes family borrows my vehicle. I am considering mounting the sensors(those black bumper dot thingies) from an aftermarket parking sensor onto the right-hand side and front and rear corners of my car's bumpers. Looks wouldn't be too great an issue because the sensors would be mounted onto unpainted black plastic portions of the bumpers and would be relatively unnoticable.The point where I get confused is that I've read that these things only work when the car is in reverse gear, which would reduce the possible usefulness because I'd need them when moving forward as well. Is that true?