After a nuclear war many technologies were lost to history. One of these technological marvels that was lost is the process of making rubber.
For nearly 500 years, scientists have tried to recreate it, but the materials they make are either too brittle to be used, or too soft and squishy. Rubber tires were all either destroyed or scavenged so you can’t find any more rubber tires.
Now say I am a traveler who wants to get from the east coast to the west coast, and I am repairing a car to drive there. What materials besides rubber could be used to make tires?