When watching racecars on TV we always hear commentators talking about getting heat into the tyres. But why do tyres need heat, and can you have too much of a good thing?
Most of us understand that tyres, apart from being round and black, need to provide grip to the road surface and this is done using friction. In order for a tyre to grip properly its molecular structure must deliver enough stickiness to allow the tyre grip the road. If too much heat is generated the tyre will not perform at its best, or worse - fail.
Excessive heat is unwanted in a tyre, be it on the track or road, so Dunlop has put a lot of work into its latest road tyre, the Sport BluResponse. Motors went to the deserts of the UAE to find out more from the 125-year-old tyre giant and also to see its involvement as the sole tyre supplier to the famous Dubai 24 Hour endurance race.
A tyre that runs cooler under stress will last longer but, more importantly, provide better performance. Dunlop has built a reputation as a sports tyre maker and as a consistent motor race winner since way back in 1902.
The high performance tyre market is growing. To demonstrate the firm's confidence in its new consumer sports tyre, Dunlop set up a day of technical briefings and practical testing for motoring journalists from around the globe at the famous Abu Dhabi Grand Prix circuit. We took part in a number of tests, including back-to-back tests in identical cars fitted with Dunlop tyres and rivals' tyres to see what, if any, difference we would find. The results were eye-opening.
Critically, we had a 'Wet and Dry' handling course that we tackled in Mercedes Benz C Classes. Stopping precision in the wet and dry was impressive. Lateral grip was confidence-inspiring too, and I was able to go outside my comfort zone when wet cornering with little effort.
We also tackled an on-road driving course in a Mercedes C Class AMG. Driving on six- and eight-lane highways surrounded by desert is an interesting experience, but sadly we had no rival tyres to test back-to-back. The B/A-rated Sport BluResponse did manage the occasional sand drift with ease, though.
In Mercedes SLKs we carried out a 'Dry Slalom' test to see how well sharp changes in direction and hard acceleration and braking would test the tyre. The test was on tarmac with a high level of grip, but needless to say we could not unsettle the tyre - even wheel-spinning off the starting line was difficult.
Dunlop says the Sport BluResponse is made using a special polymer compound to deliver this wet weather grip. There are large central grooves cut into the tyre that help disperse water quickly, greatly reducing the chance of aquaplaning. Dunlop uses a variable land-to-sea ratio with its asymmetrical tread design that evacuates water quicker than most. The tyre also uses a flatter tread profile, a specific bead seat system for sportier feel and a jointless belt construction to counter deformation at high speed.
Another bonus of the Sport BluResponse is impressive fuel economy. This is thanks to a 30% improvement in rolling resistance that could save the average user around €120 per annum compared to the tyre it replaces. The tyre is aerodynamically designed and when you couple this to the low heat compound, it isn't surprising that Dunlop has seen a 30% improvement in fuel consumption over the outgoing tyre. 'Short Braking Blocks' on the outer edge of the tread pattern help reduce braking distances, too. These extra stiff blocks increase road contact under heavy braking.
Another essential these days with a new tyre is the ability to protect your big alloys and that is what the MFS (maximum flange shield) does. An expanse of rubber runs around the circumference of the tyre above the wheel flange to buffer the alloy from any kerbing. The new EU tyre-labelling directive doesn't go far enough yet in Dunlop's eyes, as the firm used 50 test criteria developing this tyre.
In summary, when cornering with the Sport BluResponse you can really feel the stiffness of the sidewall construction and this is encouraging for enthusiastic driving. In the wet, grip is simply excellent. Low heat- generation at the contact area with the road is a key part of the tyre's great performance.
Back in Dubai we went to the track to see the 24 Hour race. It is an impressive affair and though not quite Le Mans (the ultimate in 24-hour race) it is still a true test of men and women, their machines and tyres! Twenty-four-hour endurance racing is a pure motorsport that makes a Formula 1 Grand Prix look like a mere appetiser.
The Dunlop setup at the track was highly professional and it would need to be with 7,000 tyres to service during the race. As a one-tyre manufacturer race, a number of tyre compounds would have been pre-selected and manufactured well in advance to meet the massive demand the 80 teams would have. There were 321 drivers taking part and each would race the equivalent of four F1 Grand Prix distances.
Computer-controlled and human-operated inventory for each team would see a seamless delivery of fresh tyres, monitoring of track performance, wear and temperature and, of course, the return of old tyres for new. The professional tyre fitters worked through the full 24 hours, ensuring that every one of the teams (representing 20 car brands) from Mercedes SLS (2013 winner 'Black Falcon') and Ferrari GTs to the little MINIs received a first-class service.
The race itself was a sensory overload of noise, burnt rubber, exhaust fumes and, of course, emotion. The sound of an SLS GT on full chatter is primal and intoxicating, while an Aston Martin changing up through the gears can make a petrol head cry with joy. During the race durability is vital and with the tyres operating at 90-100 degrees, temperature monitoring is critical. Data gathered by Dunlop from the race will eventually find its way into the tyres we put on our cars tomorrow.