This unsprung weight is cushioned from uneven road surfaces only by the compressive resilience of the tire (and wire wheels if fitted), which aids the wheel in remaining in contact with the road surface when the wheel inertia prevents close-following of the ground surface. However, the compressive resilience of the tire results in rolling resistance which requires additional kinetic energy to overcome, and the rolling resistance is expended in the tire as heat due to the flexing of the rubber and steel bands in the sidewalls of the tires. To reduce rolling resistance for improved fuel economy and to avoid overheating and failure of tires at high speed, tires are designed to have limited internal damping.