Why does a spare tire travel slower or require more energy than a pumped up tire?

Question

Sorry, i meant flat tire travelling slower. I typed the wrong word.

Answer 1

Actually, a flat tire makes more revolutions at a given speed than a normally inflated tire. This is because the flat tire has a smaller diameter and it has to spin faster to cover the same distance.
The reason it creates so much drag on the car and actually slows the car down is because it creates much more friction on the road surface than a regularly inflated tire which has only a small surface area on the road. In addition, the flat tire is also very difficult to steer because of the way in which it contacts the road.

Answer 2

A spare tire these days is not a regular tire. It's designed specifically to not take up much space.

That design is not capable of handling load like a regular tire. So you need to drive slowly on it. It doesn't require significantly more energy, though.

Answer 3

The spare tyre has worn out treads and thus makes more contact with the ground. It may also have less pressure due to leakage and thus add to the area of contact.