According to the Dunlop Marketing Department, the Dunlop RoadSmart IV is designed to be stronger for longer. Developed to fit 17 of the best-selling motorcycles in Europe, the RoadSmart IV comes in two flavours: SP for lighter and sportier machines and the GT for larger touring bikes.
And, to prove that Dunlop has faith in their product, they have kindly sent us a pair to try out and report back.
Imagine if you can three motorcyclists looking at a pair of RoadSmart IV SP tyres and wondering what to do next. We came up with all of the normal ideas for testing a tyre, but it all felt much too easy.
And then Roger mentioned a track day a Portimão on his Suzuki GSX-S750. Now there is a daft idea – We’ll fit the Dunlop RoadSmart SP tyres to the GSX-S and have Roger rag the proverbial out of them.
What could possibly go wrong?
Suzuki GSX-S750
Roger bought the GSX-S750 when he sold the 14-year-old GSX-R that he used for track days. The story went that he was done with track days and wanted a lightweight naked road bike that was sporty rather than a sports bike.
And it almost worked until No Limits sent him an email detailing three days at Portimão. Track days were definitely a thing of the past, right after the next one.
The GSX-S is absolutely standard and other than the Dunlop RoadSmart SP tyres, the only other modification Roger made was to drop the front forks through the triple clamps by 14mm to make the bike turn faster.
When you are in the same group as a couple of Aprilia Mille, a Yamaha MT09 and an MT10, plus a lot of other fancy hardware, the 81Nm of torque and 112BHP of the GSX-S750 with its standard exhaust, needed every advantage it could muster.
On the Brakes
The front straight at Portimão is 934 meters long, and the GSX-S was on the limiter at an indicated 134MPH by the gantry lights.
The braking point for the GSX-S going into turn one was the 200-meter board, with the need to scrub around 70MPH off the speed before committing to the right-hander.
Essentially the equivalent of an emergency stop from 70MPH on the road. The Dunlop RoadSmart IVs were happy to do this lap after lap, including the occasions when Roger overshot his breaking point and the ABS kicked in as he tried to shorten the braking distance.
Faith in the Front
Having faith in the front tyre also allowed the GSX-S750 to frighten some of the more exotic equipment, including a certain Ducati that Roger cheekily slipped up the inside of, on the brakes, going into the hairpin (Lagos – Turn 4).
OK, so the Ducati returned the favour on the straight, but where is the kudos in blasting past someone when you have twice the firepower?
Off Camber Turn 6
Torre Vip corner is perhaps the single biggest challenge on the Portimão circuit. Officially turn 6, the entry is downhill to the left and is off-camber. As the RoadSmart IV tyres are road tyres, Roger wasn’t using tyre warmers, preferring to use the first lap of Portimão to get the tyres warmed up and then go looking for the limit.
Using the more flowing configuration rather than the sharp hairpin, you arrive at turn six’s late apex carrying as much speed as you can, coupled with the desire to get the throttle open as soon as possible as the exit is uphill.
Meanwhile, centrifugal force is trying to push you across the track, which, being off-camber, is doing nothing to help you. And while all of this is going on, the front tyre is complaining and wanting to push wide.
Despite the abuse, the Dunlop RoadSmart IV tyres held on resolutely, and Roger ground a few millimetres from the footpegs and successfully prevented anyone who thought the standard GSX-S750 would be easy prey from slipping up the inside and pushing him wide.
Hanging on in Long Corners
As Portimão has a long straight, carrying as much speed as you can through the final turn – Galp – is vital. Every moment spent accelerating after exiting turn 15 is time when you are not on the limiter, going as fast as you can on the straight (an indicated 134MPH on the GSX-S750).
For the Dunlop RoadSmart IVs, this worked out to be an entry in 4th gear at 90mph, winding on the power to exit in 5th at an indicated 105mph, having spent 10-12 seconds on the side of the tyre.
RoadSmart IV SP Overall
There comes the point where you have maximised a corner, and you can’t go any faster, regardless of how much horsepower you have available. Tyre grip, angle of lean and ground clearance become factors that limit your speed through the corner.
Coming out of the last corner at Portimão with the GSX-S skimming the footpeg and the speedo indicating 105MPH plus, the RoadSmart IV SP tyres were not squirming or complaining. Torturing a tyre like that on the UK roads is impossible, and, no, we are not suggesting you start trying.
Nonetheless, if Roger, who runs in the intermediate group, can abuse a Dunlop RoadSmart IV on a circuit known for being hard on tyres for twenty ten-lap sessions over three days and still have fully road-legal tyres, Dunlop has got something very right with the new generation RoadSmart IV tyres.
