Explanation of Bicycle Tire Sizes

Bike tires come in a variety of sizes and widths. Each size has benefits and disadvantages that should be considered before deciding on the proper tire for you and your bike.

History

In 1870 hard rubber tires were added to the expensive high-wheel bicycle. This improvement allowed for a smoother ride. Soon after in the 1800s the pneumatic or air tire was invented by an Irish vet named Dunlop Sound. Today, bike wheels can be fitted with tube tires or tubeless tires that come in a variety of sizes.

Size

Look on the side of the tire for a set of numbers. On a road tire the first number represents in millimeters the diameter of the tire while the second number represents the width of the tire. On a mountain bike tire the unit of measurement is in inches. The first number is the diameter measured from the edge of the tire that holds the tire onto the rim and the second number is the width.

Road Bikes

Road: The 700 size is the most common road-tire diameter measurement. Narrow widths from 18 to 23 inches are used for road racing, though longer tour riders looking for comfort may use wider widths.

Mountain Bikes

Mountain Bike: Most mountain bike tires are 26 inches in diameter. The tire width is wider than on a road bike to provide greater stability and flexibility. Widths range from 1.8 inches to 2.4 inches. Larger 29-inch diameter tires are also available for mountain biking; these tires offer more contact with the ground and possibly more traction.

Other Types

Cyclocross and BMX: Cyclocross tires are usually 700 diameter tires. BMX tires are slightly larger at 20 inches in diameter.

Considerations

In addition to considering the diameter size and width of the tire, air pressure is also an important factor. For example, mountain biking tires are often not inflated to full capacity to allow the rider greater contact with the ground.

References

• Pedaling History Museum
• REI: How to Choose a Bike Tire