Dunlop Announces latest Addition to Sportmax Range

Prominent motorcycle tyre manufacturer Dunlop has launched the Sportmax Roadsmart, designed for sport touring motorcycles. This is a tyre that Dunlop is confident delivers outstanding performance on wet roads and matchless all around sport touring performance, qualities that are the fruit of more than two years global research effort.

The new tyre, which is reported to out-perform its predecessor, the Sportmax D220ST, in all areas, shows strong performance improvement on wet surfaces. This result was obtained whilst improving the conflicting demand of mileage performance, which was already recognised as one of the major strengths of the Sportmax D220ST.

“These improvements result from the combination of our latest Dunlop Sportmax hypersport tyres’ attributes with new compounding and construction technologies for an optimised performance in all riding, road and weather conditions,” said Sanjay Khanna, managing director Dunlop Motorcycle.

The sport touring radial motorcycle tyre segment, in which the Sportmax Roadsmart will compete, is experiencing swift growth, and has been expanding by 5 per cent per year over the last five years. In Europe, with more than one million tyres per year, it currently represents more than 25 per cent of the total road tyre market. Aimed in particular at riders of sport touring and GT bikes who are looking for mileage, comfort and safety in the wet, the Sportmax Roadsmart also offers the sports performance expected by roadster and naked bike users. In addition, the new Sportmax Roadsmart is suitable for supersport machines. Sizes for adventure bikes, such as BMW’s GS range, will also be available.

The tread pattern used on the Sportmax Roadsmart is all new and features the highest percentage of grooves of any tyre in the Sportmax family, thus delivering the most effective water draining within the range. During the tyre’s development hydroplaning events were simulated in order to define the optimal location for long lateral grooves that strengthen the tyre’s drainage capabilities.

In addition, the Sportmax Roadsmart’s tread design combines two key features that offer specific benefits to riders in wet conditions: The central tread area, the area most commonly used when riding in the wet (+-25° camber angle), is more heavily grooved, and deeper tread grooves in this central area maintain a good level of water clearance during the tyre’s entire life.

Multi-directional sub grooves optimise pressure distribution on the road, increasing tread life and allowing for regular wear characteristics. Furthermore, Dunlop’s cosecant curve design is precisely aligned with the resultant cornering, acceleration and braking forces generated at different angles and strengthens the pattern stiffness, permitting the use of softer compounds for better grip.

The Dunlop Sportmax Roadsmart employs what the tyremaker calls Triple Tread Compound technology, and those familiar with Dunlop’s motorsport based tyres, such as the Sportmax GP Racer and Qualifier RR, should be familiar with this combination of compounds. The tread thus features the following compounds:

Traction Compound – this compound contacts the road when the motorcycle is upright and is a tougher, cooler-running compound that maintains straight-line stability, traction, braking and longer tread life. The traction compound runs underneath the lateral grip compound to improve cornering and stability and control excessive heat generation usually associated with long and loaded high-speed road riding.

Lateral grip compound – this contacts the road when the motorcycle is leant over, and therefore incorporates a rubber compound developed specifically to enhance grip at maximum lean angle. The distribution between central and lateral compounds has been carefully selected to enhance the transition from straight running to maximum lean angle in both wet and dry conditions as well as improving the tyre’s mileage.

A different type of silica has been used in each of these compounds to optimise the balance between wet grip and mileage. Dunlop reports that a new extrusion process allows the use of a different type of silica to optimise the balance between wet grip and mileage. Furthermore, the latest generation polymers to offer longer tread life and maximum grip and fine carbon black, which gives a compound with high grip and fast warm-up time without sacrificing tread wear, has been used. All elements are bound with a resin that maximises grip and Polybutadiene for significant mileage gains.

Dunlop report that the design of the belt used in the Sportmax Roadsmart minimises dynamic growth of the tread centre at high speed, maintaining a stable contact patch, reducing distortion and excessive heat build-up. This is said to provide excellent stability when riding at high speeds, when riding with a passenger and in high wind conditions, and there are lower stresses into the sidewall for better feedback and enhanced linear steering properties. Improvements in the belt design and construction have also reduced the weight of the Sportmax Roadsmart (-0.5kg in 180/55 ZR17 size). This loss of weight has a significant influence on the reduction of the gyroscopic effect of the tyre and rim combination. This contributes to increased acceleration and steering performance and thanks to the reduced unsprung mass it also improves suspension characteristics and enhances rider feedback.

Computer Aided Design (CAD) and Finite Element Analysis (FEA) assisted greatly in the design of the tyre’s front and rear tyre profiles, and contact patch of the Sportmax Roadsmart has been improved in three main areas:
An optimised variation of contact area with lean angle gives smooth handling, progressive and stable trajectory.
The front contact patch shape is more uniform to give a better feedback.
The contact patch area of both front and rear has been increased to give more grip at maximum lean angle.

The new “balloon” shape used in the sidewall provides greater flexibility and a lower concentration of stress in the shoulder edge. This optimises the distribution of the contact patch improving rider feedback at maximum lean angle or when the bike is fully loaded.

Available in various sizes, the Dunlop Sportmax Roadsmart will be available in Europe in October 2007.

Front

110/70ZR17 M/C (54W) TL

120/60ZR17 M/C (55W) TL

120/70ZR17 M/C (58W) TL

110/80ZR18 M/C (58W) TL

120/70ZR18 M/C (59W) TL

110/80R19 M/C 59V TL *

* Specific sizes for Adventure bikes available second quarter 2008

Rear

150/70ZR17 M/C (69W) TL

150/70R17 M/C 69V TL *

160/60ZR17 M/C (69W) TL

170/60ZR17 M/C (72W) TL

180/55ZR17 M/C (73W) TL

190/50ZR17 M/C (73W) TL

160/60ZR18 M/C (70W) TL