Whitewall tires or white siewall (WSW) tires are tires having a stripe or entire sidewall of white rubber. Early automobile tires were made entirely of natural white rubber, however, the white rubber did not offer sufficient traction and endurance so carbon black was added to the rubber used for the treads. Using carbon black for the tire tread only resulted in tires on which both inner and outer sidewalls were of white rubber. Later, entirely black tires became available, the still extant white sidewalls being covered with a somewhat thin, black colored layer of rubber. Should a black sidewall tire have been severely scuffed against a curb the underlying white rubber would be revealed, it is in a similar manner that raised white letter (RWL) tires are made.