BUGATTI’s AUD$4m Chiron hypercar is being held back by tyres – as in, there aren’t any that won’t explode as the brand attempts a 450km/h new production car top speed record. The engine is there – a 1103kW, 1600Nm gravity-warping quad-turbo W16 – and the aero has been sculpted to the nth degree. Yet proving, as ever, that the four otherwise unremarkable rings of rubber are critical to the performance of a vehicle, there doesn’t yet exist a tyre that can cover the 125 metres per second without Bad Things Happening. Which means that Bugatti’s masterpiece of air-splitting engineering is going nowhere near 450km/h, until the rubber is sorted.
Tyres, as we are all constantly reminded – and learn for ourselves when we are seduced, by price, into buying a set we later regret halfway through the first wet roundabout – are important things. There’s no point paying for premium engineering if the bit connecting the chassis to the road surface is the weakest, dodgiest link. But with all brands telling you they’re the best, who do you believe?
Enter MOTOR’s annual Tyre Test. Every year we host Australia’s most thorough, most controlled performance tyre test to sort the grippy from the slippy. We’ve picked Sydney Dragway again on which to stage shoulderblockstraining tests like a dry slalom, emergency braking stop and motorkhana. We’ll then crank the sprinklers for our wet braking and lateral G disciplines in Sydney Dragway’s gigantic bitumen apron.
For this year’s car, Hyundai has supplied its much-hyped new i30 N. Front-drive, and having done many miles at the Nurburgring, it packs adaptive dampers, an electronically controlled locking diff, trick suspension, and an expertly tuned ESC – and Hyundai promises the brakes can cop a proper pounding. Its 19-inch wheels dictate our test’s 235/35 size, the going fitment for most of today’s fast metal.
In the name of science and all things fair, we’ll test the Hyundai on its stock rubber (special ‘HN’-specification P-Zeros) at the start, middle, and end of the day, which spits out a linear regression formula we use to adjust every tyre’s performance, accounting for changes in variables such as ambient and surface temperature, the car and driver. It generally turns out to be very minimal, but fair is fair.
Warren Luff, MOTOR’s gun driver and Supercar hot-shoe, is Our Man – the best in Australia for testing tyres, with more than a decade’s experience doing so. Although some brands couldn’t put their rubber on the line, or didn’t want to (cough, Michelin – a real pity we couldn’t include the new Pilot Sport 4S) it hasn’t stopped us from gathering the best tyres on sale. Originating from Italy to Indonesia and everywhere in between, they represent the market’s wide range of prices and, as we’ll see, performance. See the lineup for yourself in our panel on the right. And with all that out of the way, let’s get on with it.
11 PERFORMANCE-FOCUSED HOOPS AFTER YOUR HARD-EARNED CASH
SPEED freaks may hate chicanes for making racetracks slower. We think, however, they test a less appreciated side of a car’s performance. The rapid weaving quickly shifts weight from one side to the other, rolling load across a tyre. As a result, a tyre’s lateral grip, feedback, and energy recovery become crucial to slicing a chicane.
Our slalom is basically a string of them. Except, you don’t have to be a race car driver to appreciate its findings. Anyone who’s taken a bend only to discover another ‘road user’ using more bitumen than they’re allocated will know the importance of tyres that secure your side-step.
At the end of Sydney Dragway and facing a line of cones set apart at equal distances, our test sees Luffy blast through an entry gate at 45km/h. Once through, he is free to do with his right foot as he wishes, and weaves through cones in a left-rightleft fashion as quickly as possible. He repeats this five times on each tyre. We fling the best and worst results then average the remaining three.
We also use the slalom to set the day’s testing order; choosing the Dunlop first, then the Continental, the Goodyear, Falken, Laufenn, Nitto, Nexen, HiFly, Pirelli, Kumho, and finally the Achilles tyre. It’s no easy feat.
Luffy’s commitment isn’t to be argued with. After a quick scrub-in run, the i30 N’s pipes unleash a set of mighty cracks as he feathers the throttle through the cones. It quickly becomes obvious that the Hyundai snakes the slalom very well on the Dunlop, even though its special ‘MO’ compound is designed for Mercedes-Benz vehicles.
The Continental comes close to matching it, but almost every run afterwards extends the gap behind the Dunlop. Despite that, Luffy finds talent in the pack, singling out the Pirelli P Zero. “Most importantly from a driver’s perspective,” he says, “it gives good driver feel and feedback.” While that’s to be expected from rubber fitted to the i30 N at the factory, our competitive P Zero uses an ‘R02’ compound designed for Audis.
The HiFly lives on the other side of such praise. It makes the i30 N look more tail-happy than a Focus ST and the stopwatch reveals the true cost of their looseness. Because the day’s conditions suited later runs, the HiFly doesn’t get any leg-up from a theoretical advantage either.
Our linear regression’s findings only magnify the HiFly’s and Achilles’ sub-standard speed. It also penalises the Pirelli and Kumho for being the second- and third-last runs. That the Pirelli’s raw time would have put it in the top-three illustrates how the conditions got faster through the day.
SOME people are obsessed with size.You know them, their car has more pistons in each brake caliper than their engine. Each brake disc looks like a flying saucer. Meanwhile, their brake pads are rated to withstand re-entry into earth’s atmosphere. It’s likely overkill.
All that hardware means nothing if the tyre’s grip levels aren’t as large. As we’ll see, tyres can vary brake performance, along with distances, by wild margins. To test this, we’ve designed an ‘emergency’ braking zone for Luffy to use on every second return from the slalom.
It’s well away from the dragway’s sticky stuff and will involve Luffy dialling up an indicated 110km/h as he approaches the entry gate. He then will bury the brake pedal to engage full ABS from 100km/h to rest. We measure the distance it takes to stop three times, then average the result.
As Luffy cycles through the contenders, the Hyundai’s spoiler-mounted brake light flashing during hard stops, Continental shows it has evolved the ContiSportContact 5P’s braking prowess to new levels with its new SportContact 6 flagship. It pulls up a ruler’s length shorter than the Dunlop.
Even with a cool-down between each run, our control data reveals braking performance drops off slightly as the day goes on. While Luffy reassures us the i30 N’s brake pedal stays firm, surface temperatures rise steadily in both the sun and shade from around 23 degrees Celsius to around 30. Ambient temperature peaks at 26 degrees.
Because this has most likely handed our first control run an advantage over the last (it stopped 39cm shorter), this slightly tweaks our finishing order. Linear regression splits the tied placings in seventh between Laufenn and the Nitto. It also swaps the Goodyear and Pirelli in respective fourth and fifth positions, the later run Pirelli gaining the formulaic advantage.
As for the rest of the pack, Kumho’s PS91 cements its dry-braking performance with an unchanged third to replicate its result in last year’s test. Meanwhile, the pack’s tail-end is more than three metres away from the top spot.
Most notable is the Achilles, which needs an extra seven metres than the Continental to reign in the Hyundai’s 1400kg-plus at 100km/h. It’s a chilling statistic. That distance spans longer than a Mercedes Maybach S600 Pullman. Lose a game of chicken with a roo, or a set of yellow traffic lights, and those seven metres could cost you more than last place in a test.
THERE’S nowhere for a tyre to hide on a racetrack. It needs to repeatedly brake, turn, grip and go, often at the same time.And while our motorkhana circuit won’t make the Supercar’s calendar, its tight hairpins and fast sweeping right-hander is more than enough to sort one-trick ponies from true all-rounders.
Considering the course’s short length, Luffy will do three laps to reveal even the slightest performance differences. Each three-lap run is timed on a stopwatch. We have a Driftbox for back-up, but it only goes to one decimal place.
Starting off with the Dunlop, Luffy earmarks the German-made hoop’s talent early, saying “its ability to carry speed into the corner, and not wash out with any mid-corner understeer”, was really impressive. Positive signs indeed.
The Continental next makes a charge for the Dunlop’s time. It finds more grip in corners, generating an extra 0.05G, but can’t find speed elsewhere. The Goodyear and Falken then mount an attack. They end up only two hundredths apart from each other and match the Dunlop’s peak 1.03G during their runs, but can’t get within a second of its leading time.
Things gets progressively worse from here, the Laufenn, Invo and Nexen each going slower than the tyre before it. “That harder compound gives [the Laufenn] more understeer and ultimately affects the grip,” Luffy remarks. He’s similarly disappointed in the Nitto Invo, saying “you can feel the level of grip start to fall away quite early in the corner,” and the Nexen, adding “again it’s just that overall lack of grip.” Things improve when Luffy arrives smiling after testing the HiFly Challenger. “That was fun,” he blurts. “Through the sweeper, they tend to oversteer, but as they get hotter they grip up.” Though they still can’t convince the stopwatch.
The competition Pirelli does a better job by registering the first decent time since the Falken, but it’s the Kumho that puts everyone on notice. “Look out Conti,” our timekeeper says as he reads the PS91’s time. Luffy’s eyebrows are raised as he enters the pits, surprised by its turn of speed.
While the Kumho’s cracking pace would have bagged it second place in the motorkhana, the control tyre data has other plans. Its performance improves through the day, giving earlier run tyres an advantage, and thus hoists the Continental above the Kumho and into second place. But that’s the single change in the whole field and leaves the Dunlop as our motorkhana lap-meister.
One very big thanks
F1 PIT crews are slick, but they rarely do half the 15 tyre changes MOTOR’s Tyre Test requires in a day. That’s why we partner with JAX Tyres every year for logistical and tyrechanging support during our Tyre Test. Not only can they talk the treadwear talk and shoot the speed rating breeze, but they can get through the 60 single wheel swaps quicker than we can serve them. Each wheel is bolted back on to exact torque ratings, tyres are pre-marked for their correct corner, and pressures are set exactly as placards say. Of course, you’re only as good as your tools, and no sidewall can defeat the Eagle SMF equipment and its operators, also on hand to help us out. So next time you’re up for a tyre change make sure you head over to jaxtyres.com.au or give them a bell on 1300 367 897. Tell them we said thanks.
FORMULA One’s wet-option tyre can disperse 85 litres of water a second. When an F1 car is scything through a wet track at top speed, that would mean its four hoops can displace more than 20,000 litres every minute.
You can thank an F1 tyre’s cuts and grooves for that fire-hose worthy flow. Your tyres have them as well, they’re called tread patterns. And when clouds cry, their job is to bite into the road surface through a film of water. This braking test is designed to reveal if they add more than just an aesthetic look.
We’ve placed two impact sprinklers along a 30 metre stretch of tarmac. They won’t send Noah after an ark, but they drench the surface nice and evenly to leave small pools of standing water. Luffy will barrel into the braking zone with ABS fully engaged, like the dry-braking exercise, allowing the Driftbox to measure the distance it takes for the Hyundai to go from 70km/h to rest. It’s repeated three times before we rank the averages.
The Dunlop’s chances are smothered early when the Continental’s first stop matches the Dunlop’s best. The SportContact’s chunky tread blocks and minimal cuts prove more water-loving than anyone could imagine. That’s not the same story for the Goodyear. Traditionally keener for a swim than a Pommy at Bondi, the Eagle F1 Asymmetric 3 needs another two metres to arrest the Hyundai.
Falken’s FK510 starts off with a 19-metre stop to signal there’s still fight in this tyre. And its brilliance is only magnified by the Laufenn’s lack of it, as the Indonesian-made tyre sails along to 22 metres on its first try. While the Laufenn is claimed to be a comfort-focused tyre, there’s nothing comfortable about colliding with a courier van’s rear bumper because your tyres can’t pull up fast enough.
The Kumho, our second-last tyre to run, makes an unbelievable lunge at the top spot by either matching or beating the Continental on every stop. As it turns out, though, the day’s warmer temperatures gifted later runs an advantage. And the Kumho’s re-calculated score dissipates its chances for first place.
The Achilles makes another trip to the bottom of the order. Its 22.24m average distance is about 14 per cent worse than the best. There is some good news for the bottom half of the field, though. Luffy says the Nexen has enough braking feel to give the driver decent confidence.
Warren Luff, our gun driver
HE DRIVES Supercars and Time Attack machines, but outright speed and ability isn’t the only reason Warren Luff is our go-to when we need to know how fast something really is. It’s his ability to contribute insightful impressions about equipment that makes the Luffster invaluable to our operations.
His lap times are almost metronomic. On the Laufenn during the motorkhana he bung in two identical lap times and then trailed by only one tenth on the last. And standing as proof that he’s been in the thick of the world’s toughest endurance racing, you won’t catch him wasting a second out of the car, either. He’s always doing what he can to keep the Tyre Test, a machine of many parts, ticking along smoothly. Keep an eye on the lightning quick legend we call Luffy on Facebook, Twitter (@wazzaluff) and/or Instagram (@luffy76).
WHAT do you think is the most brutal thing Luffy’s body endures every year? Is it the countless laps at Bathurst in cars that would make a GT-R Nismo whimper? Dragging door mirrors along the ground while stunt driving at Movie World? Nope. On his calendar, today is the most unforgiving. “It’s the lack of bolstering,” he says, in a road car that completes 70 slalom runs, 84 emergency stops, and 14 motorkhanas that take its toll.
Based on this, it would be cruel to add lateral G tests to his roster. However, it’s crucial to know which tyre will turn on a soggy surface. So we’ve set up a right angle corner to be taken at 45km/h in both directions three times. We’ll toss the best and worst lateral G figure, average the remaining four, and rank the tyres accordingly.
The Dunlop starts off strong with some stratospheric peaks around the 1.08G mark, but its average is quickly sunk by a couple sub-1G figures. To make matters worse, the Continental SportContact 6 wastes no time in establishing its dominance. It consistently registers lateral acceleration above 1G. Amazingly, this equals an average higher than the peak G any tyre could manage during the dry motorkhana.
Goodyear’s Eagle F1 produces nothing remarkable, however, the Falken FK510 paddles through the water like it has webbed feet. It spikes at 1.08G and drops to less than 1G in only one considered run. Interestingly, our middleorder tyres can’t swim anywhere near as well. The Laufenn fails to pip 1G on the Driftbox, while the Invo’s considered runs range between 0.9G and 1G. They’re bettered by the Nexen, which hovers around the 1G mark more consistently.
Like our wet braking test, a warming surface starts to affect the control tyre performance. Its peak G climbs slowly, as does its average, which may be why the HiFly registers a 1.04G spike in the afternoon. The Pirelli, which follows the HiFly, makes the most of the warmth, producing more than 1G on every run like the Continental. A few sub-1G turns from the Kumho, though, suggest the Pirelli’s own merits rather than a warmer surface are responsible for its performance. Meanwhile, the Achilles can’t capitalise on the day’s best conditions and again turns in a lowly result.
That said, once we zap the data with linear regression the adjusted results downgrade the Kumho’s and Pirelli’s average lateral G and lift the Dunlop’s. The Continental and Falken are also boosted by the advantage of running early, but they secured their top places with or without it.
CONTINENTAL SportContact 6
SO HOW has MOTOR’s 2018 Tyre Test panned out? Like previous years we’ve decided our champion as simply as possible. Each tyre’s placing contributes towards a total score. The tyre with the lowest score wins.
It was a two-horse race between Continental and Dunlop until the wet tests exposed a chink in the latter’s armour, but there’s been plenty else happening down the order. The Kumho, Pirelli, and Falken’s collective scores were closer bunched; however, they specialised at different things. The Falken loved the wet stuff, going as far to give our Continental a scare on the lateral G. The Kumho also worked well in puddles, but its braking performance was truly impressive.
If you want consistency, though, then pick the Pirelli P Zero. Luffy said early on, “it does everything you want it to,” and while it didn’t top any discipline, its four fourths highlight that.
Goodyear’s Eagle F1 started strong in the slalom, but seems to have developed hydrophobia compared to predecessors. The old Eagle F1 Asymmetric 2 once dominated the wet weather tests.
Even so, the gap between the Goodyear and the HiFly is the order’s largest, suggesting from here on you’re trading performance for price. The only highlight in the bottom five was the Achilles’ motorkhana run, where it placed ahead of the Goodyear and Falken.
On equal placing to the Achilles is the Nitto. It didn’t excel anywhere. Like the Laufenn it’s claimed to prioritise comfort and noise levels over outright performance, but that’s a bit like bringing a pea-shooter to a gun-fight.
Joining it in last place is the Nexen N’Fera SU1. It didn’t flounder in the wet, but its dry results shows it’s no performance king. That title goes to the Continental SportContact.