Got a bike? What about the right tires for your ride? Understanding the basics of tire sizing, tread selection, and a few other common features will help you choose wisely when it comes time to shop for replacement tires.
Bike tire dimensions are indicated by two numbers, such as 26 x 2.0 or 700 x 25, listed on the tire’s sidewall. The first number indicates the tire’s diameter as measured from bead to bead, or the inner edge of the tire that secures it to the rim. The second refers to the width of the tire. To keep your brain active in both metric and imperial measurements, the dimensions for wider tires are represented in inches (such as 26 x 2.0), while those of skinnier tires—often referred to as 700c tires—are given in millimeters (such as 700 x 25).
When shopping for a tire, you must first match its diameter to the bike’s wheel, or rim. Most mountain bikes, cruiser bikes, and some commuter bikes use tires with a 26-inch diameter. If your bike has skinny tires—as most road, touring, and cyclocross bikes do—it probably requires a 700c tire. Other sizes exist, including 29- and 27.5-inch versions for some mountain bikes, and 20-inch tires for most BMX and kids’ bikes.
Bike tire width varies depending on intended riding surface, from rugged off-road trails to chewed-up asphalt to smooth-cycling pavement. Wider tires put more rubber on the road, which provides better traction and a smoother ride but increases rolling resistance (and thus pedaling effort). Skinnier tires are faster with lower resistance but offer less traction and a bumpier ride over rough terrain.
For mountain bikes and other wide tire styles, widths of 1.8 inches to 2.4 inches are most common. Larger 2.5- to 3-inch tires cater to more extreme off-road riders who take on significant rocks, roots, and bumps. For road bikes and other skinny tire options, most widths fall in the 25mm to 32mm range, with skinnier options (18mm to 23mm) available for speed racers and wider styles (32mm to 40mm) for those seeking stability and comfort. “Fat tire” bikes, a small but growing genre, use ultrawide tires and rims for grip on snow, sand, and other loose surfaces.
Choosing the right tread for your tires is a balance between speed and grip. As a general rule, more tread means more traction but also more rolling resistance. “Slicks” are smooth or nearly smooth, ride fast, and perform best on unblemished asphalt—a solid choice for bike commuting on well-maintained roads. They can be treacherous, however, when cornering in wet conditions. “Semi-slicks,” which feature a smooth middle with treads on the sides, are a good compromise.
Another option is an inverted tread, featuring a pattern of curved or linear depressions in the rubber. These are an excellent all-purpose choice for variable road conditions and occasional off-road riding. For maximum traction (and rolling resistance), a wide range of “knobbies,” tires with significant raised treads, are available. Most mountain and cyclocross bikes come with these tires when you buy them at the shop.
Bike commuters and other high-mileage riders should consider puncture-resistant tires, with thicker rubber or Kevlar-reinforced sections for maximum durability. Foldable tires pack down smaller and are easier to transport—a good, though more expensive, choice for long-distance bike touring. Winter riders may want a pair of studded tires, which feature small metal studs for traction on snow and ice.