Is there a more emotive subject than which motorcycle tyre is best?
We all have a favourite – that tyre that suits how you ride and the bike you own, the one that gives you the most feedback and confidence.
But what makes one motorcycle tyre different from another? How do motorcycle tyre manufacturers achieve the difference in a tyre’s characteristics that gives us such a range of tyres to choose from?
Cross-Ply and Radial
The original construction method – cross-ply – was developed by John Boyd Dunlop in the late 1880s. Cross-ply refers to the cords that are aligned at 45-degree angles to each other, across the centre line of the tyre.
This construction method produced a flexible sidewall when the tyre was shaped, which acted as part of the motorcycle’s suspension.
By the late 1980s, improvements in suspension and, most importantly, a significant increase in motorcycle performance created the need for a more rigid motorcycle tyre. To achieve this radial construction, patented by Michelin in 1946, where the cord is laid at a 90-degree angle to the rotation of the tyre, became popular.
Wrong Tyres
If radial tyres are fitted to a motorcycle designed for cross-ply tyres, it is possible to overwhelm the suspension, resulting in a nervous and twitchy ride, as the overall design of the motorcycle expects the tyre to flex more than a radial tyre is designed to do.
Dunlop, Bridgestone, Michelin, and Avon all manufacture cross-ply tyres today. Many retro-styled motorcycles, such as the Royal Enfield Classic 350, Kawasaki’s W800 and Vulcan 900, and early Royal Enfield Himalayan models, are designed for cross-ply tyres.
Motorcycle Tyre Construction
Typically, it all begins with an airtight synthetic rubber that eliminates the need for an inner tube, provided the wheel is also designed to prevent air from escaping.
The first ply is then added, acting as an anchor to hold the metal beads in place on the airtight layer. It is the job of the beads to hold the tyre tight against the wheel rim.
The subsequent layers, typically made from nylon, polyester, and aramid fibres in varying quantities and thicknesses, provide the tyre with stiffness and damping, contributing to the feel the tyre is designed for.
Over the core, either a cross ply or a zero-degree radial cord (spun across the tyre in the direction of travel) is then layered.
The final part of the carcass for Dunlop & Avon motorcycle tyres is the jointless belt. This belt further constrains the tyre and also resists distortion at high speeds, ensuring the tyre maintains its designed shape.
Every layer, including the airtight layer, is used to control the stiffness and running temperature of the tyre. They all have an impact on the final product.
Flat To Round
As many components as possible are applied to the carcass once it has taken its designed profile. This includes winding fine strips of compound to the tyre to ensure uniformity and high quality.
Historically, a flat tread was laid on the carcass, and then the tyre was shaped. This meant flat components being forced into a curve, causing localised high and low spots in the tread. Thankfully, motorcycle tyre manufacturing techniques have moved beyond this. How it is done today, I’ll get to in a moment.
On top of the now-formed carcass, the rubber that will be on the road is laid. As the diagram shows, this is when the different compounds of rubber are added to the tyre.
Typically, the centre is a harder material than the edges, as the centre receives more wear. In OEM tyres (copies), it is often the case that the whole tyre surface is made from the same compound, and it isn’t always the compound as found in the centre of the genuine tyre.
Tread
At this point, the tyre resembles a slick and is placed into a curing mould to bond the layers together, and if required, impress the tread pattern onto the face of the tyre.
To push the tyre into the corners of the mould, the inside of the tyre is filled with a hot liquid (in a bag) under pressure. The heat of the liquid causes the materials used in the tyres’ construction to bond (a process referred to as vulcanising), and we are left with a motorcycle tyre.
Compounds
Although we often refer to tyres as being made from rubber, they are a blend of rubber mixed with other compounds, including sulphur, which is used in the vulcanisation process, hard-wearing carbon black, and silica, which plays a crucial part in a tyre’s wet weather performance and in reducing rolling resistance.
Silica interacts differently with water than traditional carbon black, allowing the rubber to remain more flexible at lower temperatures. This flexibility increases the contact patch’s ability to conform to the road, improving grip in wet or cold conditions.
Silica also reduces energy loss as the tyre deforms and recovers while rolling, resulting in better fuel efficiency. A silica-rich compound will also reach its optimal operating temperature more quickly, a significant advantage on a cold morning.
Adjusting the silica-to-carbon black ratio in a tyre compound shifts the balance of performance traits. Add more carbon black in favour of silica, and you get a tyre with better dry grip, a higher resistance to wear and a tyre that is more durable under heavy loads and heat.
For example, sport-touring tyres like the Dunlop RoadSmart IV incorporate more silica for all-weather versatility, while track-focused tyres like the Dunlop D212 GP Pro utilise more carbon black for enhanced heat tolerance and dry grip.
Where Can I Find …
- Dunlop Motorcycle Tyres – Official Site
- Stepping – When your tyres are done
- Tyre Life – The Life Cycle of Motorcycle Tyres
Operating Windows
Nearly every component of the tyre has an optimum operating window. Go too high or too low, and the performance will be impacted. Perhaps the most important of these is the inflation pressure, which affects how the tyre flexes as we ride.
Then there are considerations such as weather conditions, temperature, wear levels and load. Tyre companies aim to create the highest performing tyres across the broadest range of factors. Not the easiest of jobs.
Bottom Line
Cross-ply or radial. High silica or carbon black. The side wall construction and how the carcass of the tyre is formed all differ from one model of tyre to the next, let alone the brand of tyre you have a preference for.
The tyre that works well on one motorcycle is not guaranteed to work well on another, regardless of how much we liked it on the previous bike.
No wonder there are so many different opinions, when someone asks – What’s the best motorcycle tyre?
Thank You
Our thanks to Stephen Bickley, Senior Race Engineer in Dunlop’s Moto Race Team, for his advice and guidance while writing this article. Any mistakes will be mine and mine alone.
