One of the most important factors that determine your bike’s performance is the size of its tires. Choosing the right tire size for your gravel bike depends on several factors, such as the terrain you ride on, your bike’s frame clearance, and your personal riding style.

This guide will help you understand what size tire for gravel bike is fit for your needs.

What Size Tire for a Gravel Bike?

Gravel Bike Tire Sizes

Gravel bike tires generally fall between road bike and mountain bike tires in terms of size. Here are the most common sizes:

Tire Width

32–38 mm: Ideal for smoother gravel roads and light off-road trails. These tires are faster and more efficient on pavement and hard-packed dirt.
40–45 mm: A versatile option for mixed terrains, providing excellent grip and comfort on rougher trails without sacrificing too much speed.
45–50 mm (or wider): Best for loose, technical terrain and bikepacking adventures. Wider tires offer increased stability and cushioning but may be slower on paved roads.

Wheel Diameter

700c Tires: The most common size for gravel bikes, offering better speed and efficiency on mixed terrain.
650b Tires: Smaller in diameter but wider, 650b tires provide extra comfort and traction, making them ideal for rougher trails or bikepacking.

Understanding what size tire for gravel bike works best depends heavily on the terrain you plan to ride and the type of experience you want.

Gravel Tire Number Decoding

To better understand tire sizing, let’s decode a common gravel bike tire example: 700x40c.

700: This refers to the tire’s diameter in millimeters, which is common for most gravel bikes. It is equivalent to a 29-inch wheel.
40: This is the width of the tire in millimeters. A 40 mm width provides a great balance of grip, comfort, and speed, making it perfect for mixed terrains.
C: This letter historically refers to the tire’s classification under the French system for wheel sizes.

For example, if you choose 700x40c tires, you’re selecting a 700 mm tire diameter with a 40 mm width, which fits perfectly for gravel bikes with moderate frame clearance.

Factors to Consider When Choosing Tire Size

1. Frame and Fork Clearance

Check your bike’s specifications to determine the maximum tire width it can accommodate. Most gravel bike frames are designed to fit tires between 40–50 mm, but it’s essential to verify the clearance to avoid rubbing on the frame or fork.

2. Terrain

Smooth Gravel and Pavement: Stick to narrower tires (32–38 mm) for less rolling resistance and better speed.
Mixed Terrain: Opt for 40–45 mm tires for a balance of comfort, grip, and speed.
Rough Gravel and Technical Trails: Wider tires (45–50 mm or more) offer better traction and shock absorption.

3. Riding Style

If you prioritize speed and efficiency, go for narrower tires with less aggressive tread patterns.
For comfort and off-road capability, choose wider tires with more tread.

Tire Pressure and Performance

The tire size you choose impacts the pressure you should run:

Narrow Tires (32–38 mm): Higher pressure (50–70 psi) for better rolling efficiency on smoother surfaces.
Wider Tires (40–50 mm): Lower pressure (30–50 psi) for increased traction and comfort on rougher terrain.

Tubeless tires are popular among gravel riders, as they allow for lower pressure without the risk of pinch flats.

Tire Tread Patterns

Tread patterns also influence performance on different terrains:

Minimal Tread (Slicks): Best for hard-packed gravel and pavement.
Semi-Knobby Tread: Ideal for mixed terrain, providing balance between speed and grip.
Aggressive Knobs: Perfect for loose gravel, mud, and technical trails.

When determining what size tire for gravel bike is right, consider the tread pattern that suits your riding style and terrain conditions.

Conclusion

The right tire size for your gravel bike depends on your riding preferences, terrain, and bike compatibility. Generally:

Choose 32–38 mm for smoother surfaces.
Opt for 40–45 mm for mixed terrains.
Go with 45–50 mm or wider for rough, technical trails or bikepacking.

By considering your bike’s frame clearance, tread patterns, and terrain conditions, you’ll find the perfect tire size for your gravel bike.

What Size Tire for Gravel Bike