Will a Different Wheel Size from OEM Fit & Affect the Bikes Electronic Aids?

Original Question: I want to install a wheel size that is different from OEM. How do I know it will fit, and will it affect any of the bike’s electronic rider aids?

In the world of aftermarket wheels, your application's sizing options can seem endless. Outside of choosing an OEM-size wheel or one based on your personal preference, below is some information to consider when purchasing wheels for your bike.

When picking wheel sizes different from OEM, either because of availability or personal preference, you must consider items such as the overall wheel diameter, tire width, and load capacity. Here is a description of the items to consider before purchasing:

1. When changing the diameter of the wheel, whether larger or smaller, items such as the speedometer, odometer, braking, and traction control can be affected. In reality, the bike's electronics do not know what size rim it has, but the overall diameter, including the tire. This overall diameter is what is used by the computer system to calculate speed. So, if your bike comes equipped with 16” wheels from the factory, you can install 17” wheels with a lower aspect ratio tire and still maintain the overall diameter. If making a large jump in wheel diameter (typically +/- 3” or more) then the electronics may need to be reprogrammed or “intercepted”, and the bike may need custom fenders to allow for clearance as large differences cannot be compensated by the tire. Overall diameter changes up to 1% should fit directly and not affect any of the electronic rider aids.

Example Overall Wheel Diameter Calculation:

Overall Wheel Diameter = 2 * Tire Height + Rim Diameter

Tire Height = Aspect Ratio * Tire Width

Note: Actual Diameters can vary slightly depending on the tire manufacturer. Most tire manufacturers list the overall diameters on their websites. You can use the information from the tire manufacturer's website when it's available, since it will be more precise than this calculation.

2. When changing the width of the wheel, high and low-speed maneuvering can be affected along with ride quality. Generally, wider wheels are more stable at high speed but decrease road feedback to the rider. Once again, this is based on the tire size, not the wheel width. Because tires have a flexible sidewall and can fit on several rim widths. Wheel widths slightly differing between the aftermarket and OEM sizes make little difference. An example of this would be going from a 3.0” wide wheel to a 3.5” (or vice versa). Most tires for these two widths will be completely interchangeable (at the same rim diameter).

Note: Recommended tire width for rim sizes can vary from each tire manufacturer. Please check the tire manufacturers' website for recommended rim widths for their tire sizes.

3. The static load rating is the last item when selecting the proper wheel for your bike. This is the weight the carbon fiber wheel has been certified to carry when at a standstill. While many variables go into the design of the wheel, this rating is given to the customer so you have the ability to know that the wheel can support the loads it will be exposed to. While this rating is usually far and above what is required for sportbike applications, it is something that needs further consideration for American V-Twin applications. For more details on static load ratings, visit BrocksPerformance.com or click on the link here.