Alloy wheels are automobile (car, motorcycle and truck) wheels which are made from an alloy of aluminum or magnesium metals (or sometimes a mixture of both). Alloy wheels differ from normal steel wheels because of their lighter weight, which improves the steering and the speed of the car, however some alloy wheels are heavier than the equivalent size steel wheel. Alloy wheels are also better heat conductors than steel wheels, improving heat dissipation from the brakes, which reduces the chance of brake failure in more demanding driving conditions. Alloy wheels are also considered more visually attractive than hubcaps.[weasel words] Alloy wheels are more expensive than standard wheels, and thus even though they are becoming more available and are standard on higher-priced models, they are not standard on many cars. Alloy wheels are prone to Galvanic corrosion if appropriate preventive measures are not taken.