The final factor in determining whether a vehicle will stop is?

The final factor in determining whether a vehicle will stop effectively is the contact between the vehicle and the road through the tires. This contact is critical because it directly influences the vehicle's ability to decelerate and come to a complete stop. The tires are the only part of the vehicle that makes contact with the road surface, and the condition of the tires, including their tread depth and inflation level, significantly affects grip and traction.

When a driver applies the brakes, the stopping power is reliant not only on the braking system but fundamentally on how well the tires can maintain traction with the road. If the tires cannot grip the surface adequately due to poor conditions (like wet, icy, or loose surfaces) or due to improper tire maintenance, the vehicle may skid or fail to stop in the expected distance.

In contrast, while aspects such as the adjustment of the brakes, the amount of friction, and driver alertness are important in overall vehicle operation and safety, they do not directly determine the final stopping ability as critically as the contact between the vehicle's tires and the road.