Final answer:
All American passenger cars manufactured since the early 1980s have been factory equipped with 1. radial tires.
Step-by-step explanation:
All American passenger cars manufactured since the early 1980s have been factory equipped with 1. radial tires. Radial tires have a structure where the innermost layer of the tire is perpendicular to the rim, providing enhanced stability and durability.
This design allows the tire to absorb shocks and provide better traction on the road, resulting in improved fuel efficiency and a smoother ride.