Why do trains use steel wheels on tracks?

Answer: Steel-on-steel has low friction

Steel-on-steel has low friction ✓ — Correct! Steel wheels on steel rails create remarkably low rolling resistance (friction coefficient ~0.001-0.002). This means trains can pull extremely heavy loads very efficiently—a single locomotive can pull thousands of tons. Rubber on pavement has much higher friction (~0.01-0.02). Low friction makes trains energy-efficient for heavy freight, though it does mean longer braking distances.

Rubber wheels would melt on tracks — Wrong. While rubber would wear faster than steel under heavy loads, it wouldn't melt. Trains use steel for efficiency—steel-on-steel friction is much lower than rubber-on-pavement, allowing trains to pull massive loads with less energy. This ultra-low friction is why trains are so efficient for heavy cargo, though it does require longer braking distances than vehicles with rubber tires.

Steel wheels cost less than rubber — Wrong. While steel wheels are cheaper long-term due to durability, the primary reason is physics—steel-on-steel creates very low rolling resistance, making trains extremely energy-efficient for pulling heavy loads. Rubber tires would create too much friction, wasting energy and limiting load capacity. The efficiency advantage vastly outweighs cost considerations.