When it comes to building or modifying motorcycles like cruisers, bobbers, choppers, and other custom bikes, there are countless elements to consider. One of the most crucial is the tire and rim ratio, which plays a significant role in the bike's overall performance, aesthetics, and handling. In this post, we’ll break down the importance of selecting the right tire and rim size, and how this choice can impact your motorcycle's ride quality, stability, and style.
WHAT IS TIRE & RIM RATIO?
The tire and rim ratio refers to the size of the tire in relation to the width of the rim it is mounted on. This ratio affects everything from the bike’s handling to the aesthetics of the build. Tires are typically identified by a set of numbers printed on the sidewall, such as 120/70-18, where:
120 is the tire width in millimeters,
70 is the aspect ratio (the height of the tire as a percentage of the width), and
18 represents the rim diameter in inches.
For heavyweight motorcycles like cruisers, bobbers, and choppers, selecting the right tire and rim size is about balancing performance with style. Here’s how different aspects come into play for each type of motorcycle.
CRUISER MOTORCYCLES
Cruisers are known for their low, comfortable ride and relaxed handling, making them a favorite for long-distance touring and laid-back cruising. When it comes to tire and rim ratios, cruisers often run wider tires, which not only look fantastic but provide added stability and comfort on long rides.
IDEAL TIRE & RIM RATIOS FOR CRUISERS:
Tire Width: 130mm to 150mm for the front, and up to 250mm or more for the rear.
Rim Size: 16" to 18" rims are standard, although larger rims can be used for custom builds.
Tire Aspect Ratio: The aspect ratio for cruisers tends to be lower, often around 70 or 80, providing a larger sidewall height that contributes to better shock absorption.
The wider rear tire often found on cruisers gives the bike a more aggressive, muscular stance while improving traction, especially on long straightaways. The combination of a wide tire with a big, sturdy rim results in excellent straight-line stability, perfect for cruising at high speeds or on uneven roads.
BOBBER MOTORCYCLES
Bobbers are stripped-down, minimalist bikes that typically feature shorter, more compact frames. The tires and rims on bobbers need to strike a balance between performance and the classic aesthetic associated with this bike style. Bobbers tend to favor a more classic, vintage look, often using smaller, more narrow tires compared to cruisers.
IDEAL TIRE & RIM RATIOS FOR BOBBERS:
Tire Width: Front tire widths around 90mm to 120mm and rear tire widths of 130mm to 150mm.
Rim Size: 16" to 18" rims, depending on the size of the frame and the style of the bobber.
Tire Aspect Ratio: A mid-range aspect ratio, usually between 70 and 80, will maintain a classic, vintage look while offering an acceptable level of comfort and handling.
Bobbers often use a more narrow tire on the front to create a lighter, more agile feeling. The rear tire can be wider for added stability, particularly for riders looking to enhance their comfort during long rides.
CHOPPER MOTORCYCLES
Choppers are known for their extended, custom frames and unique, artistic designs. When building a chopper, the tire and rim size is often a matter of personal preference and the bike’s overall visual style. Chopper builders are known for creating bikes that make a bold statement, and this is especially true when it comes to choosing oversized or highly stylized tires and rims.
IDEAL TIRE & RIM RATIOS FOR CHOPPERS:
Tire Width: 120mm to 150mm for front tires, with rear tires ranging from 200mm to 300mm or more, depending on the custom build.
Rim Size: 16" to 21" rims are often used, with larger diameters often seen in custom builds.
Tire Aspect Ratio: The aspect ratio typically falls in the 70 to 90 range, depending on whether the builder is going for a more classic or more modern look.
In choppers, wide tires with a low aspect ratio are often chosen for their dramatic appearance. These wide, low-profile tires give the bike an imposing stance and ensure plenty of traction. However, this type of setup can be challenging to handle, especially when cornering, due to the increased weight and rolling resistance of wider tires.
CUSTOM MOTORCYCLES
Custom motorcycles come in all shapes and sizes, so the tire and rim ratio will vary greatly depending on the builder’s vision and the intended use of the bike. Whether you’re designing a café racer, a sport cruiser, or a custom bobber, the goal is to select tire and rim sizes that complement the design and purpose of the bike.
IDEAL TIRE & RIM RATIOS FOR CUSTOM MOTORCYCLES:
Tire Width: Custom builds may range from 90mm to 200mm for the front and rear tires, depending on the style and theme of the bike.
Rim Size: Rim sizes can range from 16” to 21” depending on the desired look and riding performance.
Tire Aspect Ratio: Custom bikes often have a wider range of aspect ratios, from 60 for performance-oriented bikes to 80 for those looking for more comfort and style.
Custom motorcycles allow builders to play around with extreme sizes, especially in terms of wide rear tires or unique front rims. The choice between an aggressive low-profile tire setup versus a taller sidewall tire is entirely dependent on what the builder wants to achieve.
IMPACT OF TIRE & RIM RATIO ON PERFORMANCE:
While the look and stance of a bike are often the main concerns when selecting a tire and rim ratio, it's essential not to forget how these components affect performance. A few key considerations include:
Handling: A wider rear tire provides more traction but can make the bike less nimble, especially on tight corners. A skinnier tire, while less stable, can improve maneuverability. Consider the type of riding you’ll do most.
Comfort: Larger tires with a higher aspect ratio (taller sidewalls) absorb bumps and provide a more comfortable ride. Lower aspect ratios, common in choppers and some custom builds, offer a firmer ride but can lead to a harsher experience on rough roads.
Braking and Traction: Wider tires offer more grip, which is beneficial for braking and accelerating. However, they can also increase rolling resistance, reducing fuel efficiency and engine performance in some cases.
Aesthetics: The right tire and rim ratio can dramatically change the look of your motorcycle. Wide tires and large rims provide a bold, aggressive stance, while more classic builds may look better with smaller tires and narrower rims.
CONCLUSION
Choosing the right tire and rim ratio for heavyweight cruisers, bobbers, choppers, and custom motorcycles isn’t just about performance — it's about making a statement. While handling and comfort are important, the visual impact of the tire and rim size plays an essential role in your motorcycle's overall appearance. Whether you're building for speed, comfort, or simply style, understanding how tire width, aspect ratio, and rim diameter work together can help you create the perfect ride.
Consider what best suits your riding style and aesthetic vision — after all, a custom motorcycle is not just about getting from point A to point B, but about the journey and the ride itself.
TIRE & RIM RATION TABLE:
This table is a data collection from Avon, Metzeler, Pirelli, Shinko and V-Rubber to give a good indication of what tire fits what rim size. Applicable rim width for tires from other manufacturers or other than heavy weight cruisers and customs may be different.
Please note that the tire manufacturer has developed the tire on a specific rim width. For example, a 280/35VR18 Metzeler ME 880 is designed on a 10" wide rim. The tire can be fitted on a 9.50" or 10.50" wide rim, but the actual tire width will change accordingly.
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