Firestone in 1940 with a new tire mold controlled by thermostats that automatically close and open. Steam was the heat as vulcanization took place due to the chemicals that have been mixed with the rubber. Pressure exerted by the air bag inside the tire forces the rubber into the tread pattern of the mold.

https://www.detroitnews.com/picture-gallery/news/local/michigan-history/2015/04/05/life-in-michigan-in-1940/70774332/