Ever wonder about the tread pattern on your bike tires? It's the result of extensive engineering and testing. Examine your tire's treads: notice what's in the center, and then what's on each side. Side treads perform special functions when you turn your bike. Road-bike tires, for instance, often have a raised center rib or smooth surface to help reduce rolling resistance. For mountain bikes, there are now many tires specifically designed for front-only or rear-only use. A front-only tire enhances braking and steering while a rear-only tire can offer significantly improved traction. It also helps to pick the right width of tire for your weight and the type of riding you do so that the tread patterns and tire compounds suit your need.