Choosing tyres and tyre pressure

Reading tyre markings

A tyre's sidewall usually carries two markings. The inch size, for example 29 × 2.4, gives the wheel size and width in inches. The more precise ETRTO size, for example 61-622, gives the width in millimetres and the rim diameter. The ETRTO size is the most reliable when you look for a matching tyre or inner tube.

Width and rim

A wider tyre gives grip and comfort, a narrower one rolls more easily on hard surfaces. Tyre width must suit the rim's internal width – on a rim that is too narrow a wide tyre folds in corners, on one that is too wide a narrow tyre leaves the sidewall exposed. Also check the tyre clearance of your frame and fork.

Tread and rubber compound

• Low, tightly spaced tread – rolls easily and suits dry, hard surfaces.
• Tall, widely spaced knobs – grip on soft, wet and loose ground.
• Soft rubber compound – more grip, especially on wet rock and roots, but wears faster.

Off-road, riders often fit a grippier tyre at the front than at the rear, because steering and braking rely on front-end grip.

Casing

A light casing rolls fast, but a reinforced casing resists rocks and punctures better. There are dedicated reinforced casings for harder riding and e-MTBs.

Tyre pressure

The right pressure depends on the weight of rider and gear, tyre width, terrain, and whether you run an inner tube or a tubeless setup. Start within the manufacturer's recommended range (printed on the sidewall) and experiment:

• Too high – the tyre bounces, grip drops and the ride is harsh.
• Too low – the tyre feels sluggish and folds in corners; with an inner tube the risk of a pinch flat increases.

Check the pressure with a pump gauge before you ride: tyres lose air gradually. Tubeless tyres can be run at lower pressures – see our tubeless guide.