When the **tire pressure is lower than recommended**, there is an increase in **friction with the pavement**. This is because the tire deforms more than normal, which increases the contact surface with the ground. This greater contact generates more friction, which in turn causes the vehicle to require more energy to move, resulting in **higher fuel consumption**.

Additionally, a tire with low pressure heats up more, wears out faster, and can make the vehicle less stable, increasing the risk of accidents, especially in wet road conditions. Therefore, it is important to maintain tire pressure at the recommended level to ensure efficient and safe driving.