In cycling, where every component plays a crucial role in performance, safety, and comfort, the relationship between inner wheel rim width and tyre width is a pivotal factor. It’s not just a matter of aesthetics or personal preference; it significantly impacts the overall riding experience, from handling and stability to rolling resistance and traction. Understanding this relationship is fundamental for cyclists, whether they are casual riders or dedicated enthusiasts seeking to optimise their bike setup for various terrains and riding styles.

The tracklocross answer is at the bottom.

The Basics

Before delving into the intricate interplay between inner wheel rim width and tyre width, let’s grasp the basics of each component.

Inner Wheel Rim Width: The inner width of the wheel rim, commonly referred to as rim width, is the distance between the inner edges of the rim sidewalls where the tyre bead sits. It determines the ideal tyre width that can be mounted on a particular rim.

Tyre Width: Tyre width, on the other hand, refers to the width of the tyre itself when inflated. It is measured from sidewall to sidewall and is a critical factor in determining the tyre’s contact patch, rolling resistance, and overall performance characteristics.

The Dynamics of the Relationship

The relationship between inner wheel rim width and tyre width is multifaceted, with each influencing the other in several ways. Let’s explore some key dynamics:

Compatibility: The most obvious aspect of this relationship is compatibility. Not all tyre widths are suitable for all rim widths, and vice versa. Using a tyre that is too narrow or too wide for a particular rim can lead to compromised performance, safety issues, and even damage to the tyre or rim.

Tyre Shape and Profile: The combination of wheel rim width and tyre width determines the shape and profile of the tyre when mounted. A narrower rim with a wider tyre can result in a bulbous or rounder profile, while a wider rim with the same tyre may produce a flatter profile. The shape of the tyre affects its handling characteristics, stability, and cornering grip.

Optimal tyre Pressure: The relationship between rim width and tyre width also influences the optimal tyre pressure for a given setup. A wider tyre on a narrower rim may require lower pressure to achieve the desired ride quality and traction, while a narrower tyre on a wider rim may necessitate higher pressure to prevent sidewall collapse and maintain stability.

Rolling Resistance: The interaction between rim width and tyre width plays a crucial role in determining rolling resistance—the force required to keep the tyre moving forward. In general, a wider tyre on a wider rim can reduce rolling resistance by promoting a smoother transition from the tyre’s contact patch to the sidewalls. However, excessively wide tyres on narrow rims may increase rolling resistance due to tyre deformation and sidewall flex.

Finding the Right Balance

Given the complexities involved, finding the right balance between the inner wheel rim width and tyre width is essential for optimising performance, comfort, and safety. Here are some considerations to keep in mind:

Manufacturer Recommendations: Start by consulting the manufacturer’s recommendations for both the wheel rims and tyres. These guidelines often provide a range of compatible tyre widths for a given rim width, ensuring a safe and optimal combination.

Riding Style and Terrain: Consider your riding style and the type of terrain you most frequently encounter. For example, wider tyres are generally preferred for off-road or rough surfaces to provide better traction and shock absorption, while narrower tyres may be more suitable for smooth pavement or racing conditions where reduced rolling resistance is paramount.

Personal Preference: Ultimately, personal preference also plays a significant role. Some riders may prefer the feel of a wider tyre with a more supple casing for added comfort and grip, while others may prioritise the responsiveness and agility of a narrower tyre.

Experimentation: Don’t be afraid to experiment with different tyre and rim combinations to find what works best for you. Small adjustments, such as varying tyre pressure or tread pattern, can also have a noticeable impact on performance.

Considerations for Tubeless Setup: If you’re considering a tubeless tyre setup, pay close attention to compatibility with your rim width. Tubeless tyres typically have specific recommendations for rim compatibility to ensure proper sealing and performance.

Conclusion

The relationship between inner wheel rim width and tyre width in bicycles is a dynamic and intricate one, which crosses over into performance, comfort, and safety. By considering factors such as compatibility, riding style, terrain, and personal preference, cyclists can tailor their wheel and tyre setup to suit their individual needs and preferences. Experimentation and fine-tuning are key to finding the perfect balance that maximises performance and enhances the overall riding experience.

The Tracklocross Add-on

The above is really a bit of generic writing to absolve myself of any guilt if you mismatch tyres to rims. It also applies to pretty much all bikes, but for tracklocross, especially if you don’t want to blow all your money on a pretty inappropriate bike, then we can get a bit more sketchy, as sketchy means fun. Also, ride at your own risk and everything I say should be taken with a pinch of salt.

There are not many tracklocross wheelsets available off the shelf; there are, though, loads of track wheelsets available. I engaged in some scientific research (I looked at Amazon) on the most common inner width of rims on track wheels, which averaged out at 14mm. Which, I’m going to consider being closer to 15mm as I have already made my table above. The listings that don’t contain an inner width tend to suggest they fit tyres that are 19-30mm in width.

In tracklocross we are usually trying to fit the largest tyres we can in a track frame, unless we have a more specific tracklocross frame. 30-32mm is pretty much going to be the largest we can get. If you look at my little chart above is in the orange or red squares. Putting tyres this width on a narrow rim is going to make your tyre “O” shaped rather than the “U” shape that a wider tyre on a wider rim will make.

The “U” shape is more ubiquitous as it is supposed to lead to stiffer sidewalls that support you better. Which is nice. The “O” shape, though, the shape makes cornering much more fun, and the handling is more precise. It is pretty similar to the feeling of tubulars, and I guess I’m showing my age here.

I also find that “O” shaped tyres tend to grip better, I have no real scientific basis for this other than that is what I feel when out on the bike. It feels more agile, and I have definitely found the more squarish a tyre gets, the more likely it is to wash out on a corner, and we ain’t after that. Try a few different options, though and see what you prefer; you’ll probably find the “O” shape is way more fun though.