While tire lettering was previously drawn or painted onto the tires, in the late 1960s, tire manufacturers began producing white letter tires that were part of the tire. Early automobile tires were made of pure
natural rubber with various chemicals mixed into the tread compounds to make them wear better [4]. The best of these was
zinc oxide, a pure white substance that increased traction and also made the entire tire white. However, the white rubber did not offer sufficient endurance, so
carbon black was added to the rubber to greatly increase tread life. Using carbon black only in the tread produced tires with inner and outer sidewalls of white rubber, which is where
whitewall tires came from. Later, entirely black tires became available with white sidewalls being covered with a somewhat thin, black colored layer of rubber. By compressing the white rubber through the letter cutouts in the black outer layer, it gave the effect of raised white letter tires.
Mickey Thompson claims the first raised white letter tires in 1970, but many manufacturers put out similar raised white letter tires in the late 1960s and early 1970s, including
Goodyear and
Firestone. == Tire lettering resurgence with tire decals ==