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This post compares the advantages and disadvantages of 2.1″ and 2.3″ MTB tires.

Weight Comparison

The table below compares the weight of 2.1″ and 2.3″ MTB tires:

Conclusion: 2.3″ tires are about 35% heavier than 2.1″ models on average. This isn’t surprising since wider tires require more material. That said, when the models are identical, the difference is smaller.

Since MTB bikes aren’t built with lightness in mind, the additional grams are not a deal breaker but should be taken into consideration if one is trying to assemble a very light machine.

The next table compares the air pressure of 2.1″ and 2.3″ MTB tires:

Conclusion: 2.1″ and 2.3″ MTB tires operate at very similar PSI levels. That said, 2.3″ are wider and are therefore more likely to offer low PSI numbers. Ultimately, the difference in PSI depends on the models.

The Advantages of 2.1″ Tires

• Faster acceleration

It’s easier to get 2.1″ tires up to speed for two reasons:

a. Smaller wheel circumferences. Wider tires result in larger wheel circumferences. Or in other words, the diameter of a wheel equipped with 2.3″ tires is larger than that of a wheel with 2.1″ tires when all other parameters are equal.

The wheel circumference of 29″ wheels equipped with 2.1″ tires is about 2289.22mm whereas that of 29″ wheels with 2.3″ tires is 2321.13mm. Or in other words, 2.3″ tires increase the wheel circumference by 1.4%.

The larger the circumference of a wheel, the harder it is to get it up to speed. Hence why 20″ bikes accelerate so much faster than 29″ units.

b. Lower rotational mass. The lower weight of 2.1″ tires facilitates acceleration too.

• Require less clearance

2.1″ tires are narrower and thus can operate with frames and forks offering less clearance. Since MTB forks and frames are built for large tires, clearance is rarely an issue. But if you intend to use the bike as a commuter and/or a touring rig with full fenders, 2.3″ may be too wide.

• More aerodynamic

The wider the tire, the less aerodynamic it is. Hence why road bike tires designed to reduce drag are very narrow and do not protrude outside of the rim. That said, this quality is not particularly important when riding on off-road terrain as the extra grip of wider tires makes up for the “aero losses”.

The Disadvantages of 2.1″ Tires

• Less Grip

When all parameters are equal (tire tread, air pressure, wheel size…etc.), wider tires offer more grip thanks to the larger contact patch. Thus, if you want to maximize traction, the most logical choice is to get a set of maximally wide tires designed for the roads that you are going to cover (slick tires for paved roads; knobby tires for off-road).

• Smaller Suspension Effect

Wider tires provide more surface area and can operate at lower air pressure. Those properties increase the suspension effect of the tire and make the ride more comfortable.

Furthermore, the supple tire increases traction when riding on off-road terrain by making it less likely for the front or rear wheel to bounce off of an obstacle.

• More Rolling Resistance

Contrary to popular belief, narrower tires could have a higher rolling resistance than wider tires. However, this is the outcome only when the tire models are identical or close to one another and inflated to the same air pressure.

In that instance, narrower tires deform more and lose their roundness ever so slightly. In different, wider tires have a harder time deforming and remain closer to a perfect circle. Their round shape results in lower rolling resistance.

That said, the difference is quite low and close to non-perceivable. Moreover, a narrower tire can always be inflated to higher air pressure which will negate this downside.

• Worse Cornering

Narrower tires have a smaller contact patch which makes cornering less stable. Of course, the tread of the tire is very important too as it has to correspond to the surface.

The Advantages of 2.3″ Tires

The advantages of 2.3″ tires are essentially the disadvantages of 2.1″ tires, namely:

• More grip thanks to the larger contact patch and the potentially lower air pressure
• Lower rolling resistance when operating at the same air pressure as 2.1″ tires
• Higher suspension effect
• Better cornering
• Better roll-over-ability thanks to the larger contact patch

The Disadvantages of 2.3″ Tires

• Heavier (higher rotational mass)
• Larger circumference making it harder to spin the rear wheel
• Require extra clearance which can be a problem when the rider uses full fenders
• Less aerodynamic

What To Choose?

If you intend on covering difficult off-road terrain, wider tires will help. In that case, 2.3″ tires are a logical choice if your frame and fork can support them.

That said, 2.1″ tires are still wide enough for aggressive MTB riding. They are also better for commuting thanks to their lighter weight and narrower profile resulting in less drag and lower clearance requirements.