What Size are Mountain Bike Tires?

If you want to up your mountain bike game, upgrading your MTB tires can offer you a lot of bang for your bucks. How? Well, you can gain traction or even get a lower rolling resistance.

You can get tubeless tires that mean fewer flats and use a tubeless sealant to fix flats on the fly. On the other hand, you can cycle with a lower tire pressure making trails less bumpy. Lastly, you save weight as it removes a small percentage of the mountain bike’s weight.

Still, you have tons of choices, so how do you decide what works best. Luckily, we’re here to help you slap some new skins on your wheels with some helpful tips.

Wheel Dimensions

When you look at MTB tires, you find them displayed in the wheel diameter x tire width, 29 x 2.4. In mountain bike tires, you see three dimensions 26-inch, 27.5-inch, and 29-inches. You can find smaller versions for your kid’s bikes that range from 12 to 24-inch diameter.

The tire diameter can range from 1.9 inches for your ultralight race and kids’ bikes. In comparison, 5-inches is primarily for your fat bikes. So the first number is mostly the measurement of wheel size and the widths determined by how much clearance is between the fork and rear triangle with the tire by personal preference.

Hence, choosing the tire widths depends on what you’re looking for.


In general, you will look at a width of 1.9 inches to 2.25 inches for cross country tires. While for all MTB tires/ trail bikes/ Enduro, you look at a width of 2.25 inches to 2.6 inches. For downhill bikes, the width is 2.4 inches to 2.5 inches, while the plus is 2.8 inches to 3.0 inches.

Then your fat bike has a width of 3.7 inches to 5 inches. Furthermore, when selecting mountain bike tires, it helps match the tire’s width with your rim width. You can use a skinnier tire on your MTB to roll faster, but it does have lower resistance and is not ideal for loose conditions.

While fatter tires can handle well for trail riding but absorb a lot of hits with a slower rolling. You may encounter clearance issues in your bike frame using fat tires. In general, XC tires provide narrower tires while your DH tires and Trail are wider.

new tires


The outer casing of the tire is the carcass that works like a skeleton. It is rated in terms of threads per inch or TPI.

A 120 and up TPI tire size is more lightweight and supple but leaves the tire prone to pinch flats and punctures.

Still, a low TPI of 60 and below is heavier but durable. Still, it does not have the ability of a higher TPI. But it depends on your riding style and terrain. Then it would be best if you also looked at the tread pattern.

With long pointy knobs, you get better grips than shorter smooth ones. So, the design of the tire is also essential. In addition, the knob spacing needs consideration as it will affect how the grip and mud-shedding occur.

Furthermore, tires are also grouped into different tread patterns, as seen here:

  • For a low rolling resistance, you can find slick tires exclusively for the road, and for off-road riding, pay special attention to the side knobs that help with cornering.
  • Then you have maximum grip tires marked for loose or wet conditions that world well for climbing and are great downhill tires.
  • The all-rounder blends low rolling efficiency with more grip.

Then the center and side lugs are the workhorses for mountain biking as they work together to assist in cornering, while the transition lugs help with handling.


For the best mountain bike tire, you also need to look at the structure from the material, as various rubber compounds can go into the design. It is grippy and sticky with a softer rubber but wears out fast.

While a firm compound rolls slowly, it does not provide a superior grip. Hence, you find most mountain bikes with dual-compound tires. The side knobs are softer for improved grip, while the center knobs are firmer for longer life.

The Bead

The bead is the lipped edge of the tire that seats the inside of the rim. You can find the tire structure of a kevlar or wire bead. Kevlar is lightweight but is expensive and foldable, making it challenging to mount when you have a flat.

Forward vs. Backward and Front vs. Rear

A local bike shop can sell the MTB tires front/rear, while others market them as suitable for the front and back. Some cyclists prefer matched pairs and others prefer two different tires.

For example, if you have a low resistance rolling tire on the front with a frippery rear wheel, you can improve your climbing and reduce the friction upfront. Still, most tires are uni-directional, and you need to pay attention when mounting them for max performance.

Then you have bi-directional or reversible tires that can give more traction depending on the direction it rolls.

Tubed vs. Tubeless Setup

You can find tubeless, tubeless-ready, and UST tires. The UST tires you can use with a tubeless wheel set up. Still, it does come with pros and cons. The advantage is it works with a sealant system and has a lighter weight with puncture resistance. Still, installing them is more challenging, and they are more expensive.


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