Tires had been rationed due to shortages of natural rubber; however, the U.S. built synthetic rubber and nitrogen plants, aluminum smelters, aviation fuel refineries during the war.
Tires had been rationed due to shortages of natural rubber. The U.S. built synthetic rubber and nitrogen plants during the war. This was however. Synthetic rubber and nitrogen plants were aluminum smelters. Aluminum smelters were aviation fuel refineries.