Curb feelers were popular car accessories during the ’40s, ’50s & ’60s. They looked like your car was growing cat whiskers. The purpose of the curb feeler was to alert you when your precious white wall tires were getting too close to the rough surface of the cement curb–sudden death for your tires or cool hub caps.
Curb feelers are metal springs or wires that scrape against the curb when parallel parking your vehicle. As a youngster I remember the distinctive sound of metal against concrete or what I compare to scraping your finger nails on a chalkboard. 
Whenever my dad had to parallel park the car, I remember as the car got closer and closer to the curb you would hear this scraping or screeching sound that resonated throughout the car. This was due to the fact that the curb feelers were attached to the metal car body. Before knowing what these things were, I often thought to myself, what is that noise!
Thanks to all of the retro car enthusiast around, curb feelers are still around to give their ride that classic ’50s look.
Check out wikipedia.com for more details:
http://en.wikipedia.org/wiki/Curb_feeler



