Road bike tires come in a dizzying array of sizes and styles.
Background
Pneumatic tires were invented in the 19th century and were quickly adapted to bicycles. Since then, better materials and manufacturing processes have improved performance and durability, but the general design, a durable rubber casing supported by pressurized air, has remained the same.
Basic Types
Most road bikes use clincher tires, which are held on the wheel by grooves in the rim. A separate inner tube is filled with air. Clinchers are common and inexpensive. Some road bikes use tubular tires, which consist of a tube sewn into a tire that is then glued to the rim. Tubulars can perform slightly better but are harder to maintain.
Sizes
Modern road bikes use a tire size known as 700c. Older bikes might use 27-inch tires. These sizes are not compatible, but the 27-inch size is still stocked by most bike shops.
Widths
Tire width has a direct effect on comfort and rolling resistance. Wider tires are more comfortable because they have more contact with the road, but they also create more rolling resistance. A wider tire will also make your bike feel slower to respond to steering inputs.
Narrower tires are faster but less comfortable. A good rule of thumb is that wider tires are better for comfort and stability while narrower tires are better for speed.
Thinner tires offers less rolling resistance, while wider tires absorb shock and resist punctures. The 700c tire widths are measured in millimeters, from 20 to more than 40. Heavier riders should consider wider tires.
Pressure
Tire pressure is measured in pounds per square inch (PSI). The ideal pressure will vary depending on the width of your tires, but a good starting point is 80 PSI for 23mm tires and 100 PSI for 25mm tires. You can experiment with different pressures to find what works best for you.
Treads
A nearly slick tire offers the best traction on smooth, hard roads. Some amount of tread might be desirable for riding in sandy or muddy conditions.
Conclusion
Bicycle tires come in a wide range of sizes and widths to fit different bikes and riding styles. The right choice of tire can make a big difference in comfort and performance.
