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Condensed Info: If the external width of the rim is 23mm, then the rim is very likely to support 28mm tires.

If the number 23 refers to the internal width of the rim, then the rim is too wide for a 28mm tire.

Internal and External Rim Width

The external width of a rim is the perpendicular distance between the outer sides of the rim walls. Or in simpler words, the external width is the total width of the rim.

The internal rim width is the perpendicular distance between the closest points on the inside of the rim.

The inner rim width is the most commonly used data point when referring to a rim’s width as it provides information about the tire sizes that the rim is compatible with.

Below you will find a table serving as a guideline for rim and tire compatibility:

The data in the table shows that a rim with a 23mm inner width should be combined with 37-68mm/1.45-2.7in tires.

Meanwhile, a 28mm tire requires a rim with 15-20.9mm inner width.

Note: The numbers in the table are estimations. Slight deviations are possible without repercussions.

FAQ: What are the dangers of combining a narrow tire with a very wide rim?

If a narrow tire is combined with an excessively wide rim, the user can face:

• Excessive pinch flats (punctures that take place when the wheel hits a non-sharp but hard object).
• Rim damage (the narrower tire does not provide as much protection for the rim)
• Less than ideal tire to rim connection

If the number 23 is referring to the external rim width, and the internal rim width is within 15-20.9mm, then a 28mm tire will fit just fine on the rim.

Note: It’s possible that you know neither the external nor the internal width of your rims and have entered “23mm”, to indicate the tire size instead. If the wheels have originally come with 23mm tires, chances are that the internal rim is between 13 and 16.9mm. If the actual number is on the wider side (15mm+), the rim will accept a 28mm tire.

The Advantages of Switching From 23mm to 28mm Tires

• Comfort

Wider tires can operate at lower air pressure without risking pinch flats. The lower air pressure allows the tire to deform upon meeting a road irregularity. The final outcome is a smoother ride easier on the rider’s joints.

• Greater Roll-over Ability

The wider the tire, the easier it is to roll over obstacles. Hence why you don’t see mountain bikes with skinny tires. This quality makes 28mm tires better for riding on imperfect roads. A new rider may be surprised how much off-road one can go on 28mm tires.

• Lower Chances of Trapped Wheels

A slim 23mm tire can fall into a road crack or a water drain. When that happens, the rider goes over the handlebars instantaneously. Technically, the same can happen with a 28mm tire too, but the chances are notably slimmer. Hence why 28mm tires are superior for commuting purposes.

• Better Traction

If two tires have the same tread pattern, but one is wider, the wider one offers more traction and thus stability thanks to the larger contact patch.

The Downsides of Switching From 23mm to 28mm Tires

• Extra Weight

Wider tires require more material and weigh more. If one wants the lightest possible bicycle, thinner tires will help with that goal. That said, recreational riders are unlikely to experience a degraded performance from the extra grams.

• More Drag

Wider tires come with additional drag. Тhe penalty isn’t severe and will be a topic of analysis only when competing on the highest level.

• Reduced Clearance

One of the major downsides of this switch is the reduced fork and frame clearance. Truth be told, if the bike is an aggressive road or track model, it may be unable to accept 28mm tires due to their size regardless of the rim.

Also, the wider tires could make the installation of accessories such as full fenders difficult if not impossible. If one is using the bike for intensive commuting, this could be a major issue.

Summary: What You Need To Know

• If the rim has a 23mm internal width, it’s too wide to safely install a 28mm tire on it.

• If the rim has a 23mm external width and an internal width between 15-20.9mm, it can accept a 28mm tire.
• The pros of switching to a 28mm tire are a softer ride, greater roll-over ability, improved traction, and fewer chances of a trapped wheel.
• The cons of switching from 23mm tires to 28 are extra weight, drag, and reduced clearance that may prevent the use of accessories such as full fenders.