Whitewall tires or white sidewall (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.
The status of whitewall tires versus blackwall tires was originally the reverse of what it later became, with fully black tires requiring a greater amount of carbon black and less effort to maintain a clean appearance these were considered the premium tire; since the black tires first became available they were commonly fitted to many expensive luxury cars through the 1930s. During the later part of the 1920s gleaming whitewalls contrasted against darker surroundings were considered a stylish if high-maintenance bit of "flash", still too flamboyant for those with conservative tastes however. The popularity of whitewalls as an option increased during the 1930s, automobile streamlining and skirted fenders eventually rendered the two-sided whitewall obsolete. The single-sided whitewall remained a desirable option through the 1970s, becoming a hallmark of "traditional luxury" along the way.
Beginning in the early 1950s whitewall width began to diminish as an attempt to reduce the perceived height of the wheel/tire, during the decade increasingly lower vehicle heights were in vogue. Finally in 1957 the production version of the ultra-exclusive Cadillac Eldorado Brougham was fitted with whitewalls that were reduced to a 1" wide stripe floating on the tire sidewall with a black area between this stripe and the wheel rim. Wide whitewalls generally fell out of favor in the U.S. by the 1962 model year, they continued as an option on the Lincoln Continental for some time thereafter but most common were the 1"-3/4" stripe whitewalls. During the mid-1960s varieties on the striped whitewall began to appear, a red/white stripe combination was offered on Thunderbirds and other high-end Fords and triple white stripe variations were offered on Cadillacs, Lincolns and Imperials. During the 1970s the ostentatious vehicles emerging from Detroit inspired an increase in whitewall stripe width (1 5/8" plus) while full-fledged wide whitewalls had made a return within the pimpmobile culture.
Although wide whitewalls are virtually non-existent on modern automobiles, they are still manufactured in original bias-ply or radial form by specialty outlets and/or classic car restoration companies such as Diamond Back Classics, Coker Tire, Lucas Classic Tires, and Vogue Tyre Company. Some companies manufacture wide whitewall inserts - the Portawall inserts are usually sold through VW Beetle restoration companies. (Port-A-Walls should not be used with radial tires due to the flexing of the sidewall that creates friction and rubbing between the port-a-wall and the tire )
Modern trends toward more minimal styling, and large rims favoring low-profile tires leave little room for a whitewall. With the introduction of the new "retro"-styled Ford Thunderbird, Chrysler PT Cruiser, and Chevrolet HHR, whitewalls may again become popular; they continue as an available factory option on the Lincoln Town Car.