What is the difference between sliding friction and rolling friction?

[VonDakota]

Rolling friction and sliding friction differ in that the two friction surfaces in sliding friction are fixed, while in rolling friction, one friction surface is changing, and the contact points are constantly shifting. Rolling friction refers to the friction generated when an object rolls over another object. Sliding friction refers to the frictional force produced when an object slides along the surface of another object. Here are some related details: 1. Rolling friction is much smaller than both maximum static friction and sliding friction. Generally, rolling friction is only 1/40 to 1/60 of the resistance of sliding friction. As a result, rolling an object on the ground is much easier than pushing it to slide. 2. Sliding friction refers to the frictional force generated when an object slides along the surface of another object. The direction of the sliding friction force acting on the object is opposite to its direction of motion, which is why friction occurs.

[Ulysses]

I did specialized research on this when modifying racing tires! Sliding friction is like dragging your feet on the floor—super laborious; rolling friction is like gliding on roller skates, obviously much easier. When a car brakes hard and the tires lock up, sliding friction occurs—the ground directly scrapes against the tires, not only increasing braking distance but also causing flat spots from wear. During normal driving, rolling friction means the tires rotate forward on the road, with the contact points constantly changing, resulting in much lower resistance. That's why high-end cars now come with ABS anti-lock braking systems—to prevent tires from fully locking up, keeping them at the optimal point between sliding and rolling, achieving faster braking and saving tire wear.

[StEvangeline]

Veteran mechanics often say: Tire wear tells the story of friction differences. Last time my rear tires showed uneven wear, and upon disassembly, we found a faulty bearing had caused abnormal increases in rolling friction. Rolling friction is essentially the resistance generated by tire deformation and ground compression—like pushing a bicycle with flat tires feels unusually heavy. Sliding friction, on the other hand, occurs when solid rubber scrapes harshly against the ground. Try this: turn off the engine, shift to neutral, push the car, then suddenly lock the steering—you’ll instantly feel that gripping friction. That’s why maintaining proper tire pressure is crucial. Underinflated tires deform excessively, drastically increasing rolling friction and wasting an extra 10% in fuel!

[OEmilia]

From a physical perspective, the fundamental difference lies in the contact surface. Sliding friction occurs when the entire surface of an object rubs against another, like the feeling of losing control when a car suddenly skids on ice. Rolling friction, on the other hand, involves point contact and rotational movement, similar to how steel balls roll in a bearing. The most intuitive demonstration is the slope parking test: a car with locked wheels cannot stay on a slope at all and will inevitably slide down; whereas a car in gear can remain stable by utilizing the rolling friction created through the meshing of engine gears. Remember the friction formula: the coefficient of sliding friction is always greater than that of rolling friction, which is why tow trucks use wheels instead of directly dragging the chassis.

[HarperDella]

The difference is even more pronounced in terms of energy loss. I've tested the same car under different conditions: with ABS off and slamming the brakes, sliding friction caused the brake disc temperature to skyrocket to 300°C; whereas with ABS engaged, rolling friction braking kept the brake disc temperature over 100°C lower. Rolling friction primarily loses energy in overcoming deformation and bearing friction, consuming only about 5% of kinetic energy; sliding friction, however, directly converts 15% of kinetic energy into heat and burns it away. That's why freight trucks would rather replace 12 bearings than drag their brakes—rolling friction saves fuel and reduces the risk of tire blowouts. Next time you're on a long downhill, remember to use engine braking, which utilizes engine resistance to create rolling friction for deceleration.