Rear Tires and Motorcycle Safety: Debunking the Wide Tyre Myth

There is a persistent belief that wider rear tires can significantly improve motorcycle safety, but is this notion backed by facts and empirical data?

The Truth About Tire Width and Safety

The general consensus among experienced motorcyclists and motorcycle safety experts is that the original equipment (OE) tires provided by the manufacturer are often the best choice for optimal safety and performance. However, under certain circumstances, adjusting the tire size may be acceptable. It is crucial to prioritize the type of tire over its size. Multi-compound tires that offer better grip in corners are often preferred, and adherence to recommended tire pressures is essential for overall safety.

Why Wider Tires Can Be Counterproductive

Interestingly, the rear tires often come in wider sizes than necessary because modern motorcycles possess significant power. The sheer power of a modern sports bike requires a larger contact patch to ensure sufficient grip. However, in contrast to the modern setup, the weight of the motorcycle plays a crucial role in determining the ideal tire width.

The common misconception is that wider tires look cooler, which has led manufacturers to equip motorcycles with oversized tires to enhance their appeal. However, in wet conditions, the grip levels are often seriously diminished in the name of fashion.

Historical Context and Insights

To illustrate this point, we need to delve into historical examples. In 1969, the Triumph Trident, a 550lb machine with approximately 65 BHP, required a specific tire width. The innovative tire developed for the Triumph Trident was a 4.10/19, which in metric sizes translates to a 120/100/19. This tire was far narrower than any modern superbike but was the correct size for the bike's weight to maximize grip.

Modern motorcycle tests often highlight that bikes fitted with 'skinny' tires often outperform those with wider tires, even though the latter look more fashionable. The testers frequently remark that despite the narrow tires, the bikes handle and grip extremely well because the correct width provides the necessary contact patch for better performance.

The Role of Rubber Compound and Wet Weather Grip

Tire manufacturers address the issue of reduced grip by making the rubber softer, which increases adhesion. However, this compromise comes at the cost of increased wear rates, particularly in dry conditions. In wet conditions, the smaller contact patch is crucial for ensuring that the bike's weight is pressing down harder on each square centimeter of rubber, thereby improving grip.

Modern race bikes prioritize straight-line power transfer over ultimate cornering grip. Being powerful is more about straight-line acceleration, and achieving tire grip is more critical under all weather conditions. Thus, the fashion of larger tires for aesthetic purposes does not effectively translate to safer riding conditions, especially in wet weather.

Conclusion

In conclusion, while wider rear tires might seem like a no-brainer for safety, the reality is far more nuanced. Motorcycle safety primarily depends on tire type and proper tire pressure, rather than tire width. By focusing on a tire that offers the right balance of grip and durability, riders can significantly enhance their safety on the road.