MOTOR Tyre Test 2016: Wet Braking

Our fifth and final discipline isn’t a foregone conclusion, regardless of the relentless success enjoyed by the Dunlop Sport Maxx RT so far. If our previous tests were ideal-world conditions, this one is real world.

A road tyre that can’t perform when dark clouds unleash their contents is of little use to any true enthusiast driver with a high-performance daily driver. If you’ve ever experienced aquaplaning, you’ll know it’s not as fun as it might sound. When you’re driving at speed, you don’t want your car trying to do an impression of a surf board that not even Kelly Slater could control.

Fortunately, none of our 10 competing tyres could be accused of being semi-slicks. Virtually all are of the asymmetrical-tread variety – compromising optimum dry grip by featuring plenty of the deep grooves and smaller slits critical to channelling water away from the contact patch. Interestingly not one tread pattern looks alike, so it’s all down to their specific design and compound.

2

The advantages of the RS3’s all-paw grip mattered little in our wet braking test. This was more about the little cuts and grooves in each hoop 

Luffy conducts the runs with third-gear approaches, dropping the anchors while cold at 70km/h. The Driftbox records the stopping distance from 60km/h to a brake-juddering halt.

With Australia’s harsh sun baking the bitumen at up to 55 degrees surface temperature at one point in the afternoon, our water tanker was kept busy – frequently unloading the water to ensure a consistently wet test section.

If there had been any thoughts the Toyo, Nexen, HiFly and Nitto tyres had sacrificed some dry-grip performance to be superb in the wet, they were soon dispersed once the taps had been turned on.

The wet braking featured the usual suspects in the bottom four, with just Nexen and Hifly trading places (8th and 9th). The HiFly and last-placed Nitto were more than 2.5 metres off the winning distance of 13.96m. That’s a sizeable margin considering how significant every metre could be when braking in an urban environment.

Pirelli, Michelin and Goodyear occupied the midfield, closely matched in a stopping range from 15.04 to 15.57m. Hankook halted just below 15m to register an impressive third place.

And just four centimetres separated first and second. As shown in the raw data on the opposite page, Dunlop scored the win on the day to make it a remarkable clean sweep, though after our linear regression calculations were made post-testing (see breakout) the Continental was established – by the numbers – as the adjusted wet-track victor.

WET BRAKING RESULTS

We regress

Levelling the field

YOU CAN’T do much about variables, but you can get some data to show what might happen if the playing field was equal. We run a control tyre at intervals throughout the day to get a grip (sorry) on how things like surface temperature, vehicle deterioration and driver fatigue might affect the scores.

How the control tyre’s performance changes gives us an idea how the playing field might also be changing. It’s called linear regression and it’ll finish off the battery in your calculator, but basically applied to the raw data to cancel out any advantages or disadvantages a given tyre might enjoy or suffer, the only change to our final line-up was a tying of the last three places for the HiFly, Nitto, and Nexen.