MOTOR's 2021 Tyre Test

UPDATE, June 2022: Pilot Sport 5 tested!

Well, we've now driven cars fitted with Michelin's newest flagship performance rubber. To get our view on how they go, hit the link below.

"The amount of wet grip, some of it on virtually standing water, is truly impressive."

MOTOR's 2021 Tyre Test

Panic. That’s what set in when I realised that MOTOR’s 2021 Tyre Test was only days away, and I hadn’t yet checked the forecast. Call it traumatisation, but memories briefly returned of last time when biblical weather forced us to abandon the event halfway through.

That’s not to say our annual rubber torture test – back after a Covid-induced hiatus in 2020 – can’t handle a bit of rain. Just intermittent showering can undermine the predictability of data. And given Australia’s most trusted and longest running independent tyre test is built on solid bankable numbers, I didn’t want to stress thinking about how we could avoid that being compromised.

Fast forward to Tuesday, April 27. Morning dawns without a cloud in the sky as we roll into Sydney Dragway, where the space outside the scrutineering shed will be our official place of business for the day. We’re on.

Gun-driver for hire Warren Luff is already scanning the area from the passenger’s seat, mapping out cones in his mind to design the slalom, wet and dry emergency braking test, lateral G test and motorkhana within the vast area. We’ll get on to them later.

Supporting crews crucial to getting today off the ground, including the team from Tyreright that will be on the rattle guns, begin to arrive as Luffy zig zags the car park in our hire car with a boot full of orange cones.

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A ute-load of our rubber arrives next, delivering six high-performance patterns and two distinct groups of competitors. First, there are the big boys. The Michelin Pilot Sport 4 S is back to defend its 2019 win. Meanwhile, it’s flanked by the Pirelli P Zero, Yokohama Advan Sport V105 and Goodyear Eagle F1 Supersport.

Rounding out the field are a pair of budget contenders in the GT Radial Sportactive and HiFly Challenger HF805 DSRT. What was missing? Unfortunately, Bridgestone’s new Potenza Sport had not launched in time, and the Maxxis Victra VS5 missed the boat, literally – they were stuck at a port up north. Unfortunately it’s also the first time Continental did not have its always-competitive rubber in the ring since 2012.

Few cars are fit enough to put a field of tyres through their paces for any tyre test, let alone on tyres of this calibre. But the Mercedes-AMG A45 S, a 309kW/510Nm all-wheel drive turbo terror with punchy diffs and adaptive suspension, is as precise as it is explosively quick.

With 360mm brake discs and bulging six-piston calipers up front pairing with 19-inch wheels wearing 245/35 ZR19 all around (a relatively common tyre size in performance car land), the quick-footed A45 S stood up as the perfect tool to dissect our field.

Delivered with a full tank of fuel, the only preparation needed for the A45 S was to switch off ESP and turn on its Race Mode, priming its various hardware for their highest performance. And lastly, a VBOX – which we use for any competitive test where data is paramount – was plugged into the 12-volt power supply so it could track each run with satellite-linked accuracy.

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Before we unleashed Luffy, though, there were a few matters of process to clarify. The first rubber to run through our disciplines was already on the A45 S, given they are our control set. But setting them to placard pressures – 44psi on the front and 41psi at the rear – begins a process we’ll repeat again for each tyre for the sake of consistency.

Importantly, with all sorts of variables threatening to change the testing conditions throughout the day, the control tyres were tested in the morning, midday and late afternoon to reveal if a specific time is more favourable than another. We then used linear regression to adjust the raw data with a weighting based on this, eliminating any doubt about the run order favouring specific tyres.

Each tyre was run through the disciplines in the same order, beginning with a short run-in to de-glaze the tyres. The first victim was the control, followed by the Goodyear, HiFly, GT Radial and then the control again before a lunch break and re-fuel. After lunch, Luffy will finish with the Pirelli, Yokohama, Michelin and control. And with that out of the way, let the games begin...

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01: Motorkhana Course

It’s hard to spot, but down the opposite end of the carpark, a ‘race track’ hides in plain sight. Among the rectangular lawns laid in a grid are twists and turns used for a much larger motorkhana during North Shore Sporting Car Club’s tarmac rallies.

We focused on just nine of those corners for our 424m motorkhana. The exercise is an indispensable tool for tyre testing because not only are fundamentals like braking, traction and lateral grip crucial to a fast lap, but it focuses on peripheral aspects of tyre performance as well.

For instance, extra feedback helped Luffy hit his markers more precisely. Then there’s endurance. Because the course was tackled in a clockwise direction, the left front tyre was worked hard consistently until the A45 S briefly straightened out over the start-finish line at over 90km/h and then barrelled into the first right-hander again.

The results are decided on the elapsed time each tyre needs to complete three laps. And to eliminate as many variables as possible, Luffy began with a full-speed flying start.

It was quickly established that Goodyear would be the one to beat this year, despite Luffy saying the Eagle F1 suffered from some understeer compared to the control tyre. It trounced the following HiFly, GT Radial and Pirelli.

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Only the Yokohama and Michelin had the chops to knock off the Goodyear. But as we’d find out, only one of them did it convincingly enough to avoid being relegated by the linear regression-based formula.

The control tyre results revealed that they favoured conditions later in the day, improving by almost half a second overall. The formula responded to this by handing each tyre a weighted improvement, with the further a tyre was from the ideal conditions equalling a more dramatic adjustment of their results.

In the end, the Goodyear was close enough to the Yokohama on raw data to bag second place.

02: Lateral G-Force

Our lateral G-force test measures how hard a tyre can hang on to the road, full stop. Back near the motorkhana, Luffy picked out two corners that make a double-right. After approaching the first bend at 40km/h, he accelerated as hard as possible into the second, pushing the tyre to the edge of grip.

During this, a tyre inevitably might step over its grip limit and spike a reading on the VBOX. While the software already applies a smoothing value to the data to minimise any anomalies, Luffy also ran the test three times in either direction to give us a broader and more accurate range of results.

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Then, to refine them even further, we also flick the worst and best G-force figures each tyre records and then average the remaining four. Straight away, like in the motorkhana, the Goodyear set a benchmark average for the day. Its 1.0226G remained the top score until, again, the Michelin dethroned it with a dominant 1.039G average.

The differences in control tyre performance were only minor, with grip improving from an average of 1.0075G to 1.0125G. As a result the Michelin and its big grip-loving shoulder blocks, were safe.

Feeding the data into our formula only split the equally matched Yokohama and HiFly’s raw results in the latter’s favour.
And while no tyre followed the Goodyear and Michelin above an average of 1G, it’s worth mentioning the HiFly was the only other tyre that logged 1G-plus on two of its eligible attempts.

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03: Slalom Course

The slalom remains a relatively simple way to effectively size up a tyre’s performance capability for
two reasons. The repeated direction change requires good mid-corner stability, while forward momentum needs tenacious traction.

With nine cones set at equal distances over 160m, Luffy approached the first one at 40km/h and then dropped the hammer once that cone disappears past the A-pillar in his peripheral vision. From there, it’s about going as fast as the tyres allow until over the finish line.

The test was repeated four times after the first run. Once the data was downloaded and verified against Luffy’s handwritten notes, the best and worst runs were dropped to leave us with an average of the remaining three – minimising the chance of anomaly.

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Again the test was the Goodyear’s to lose. Every tyre after failed to knock off the German-made hoop from top spot until, surprise surprise, the Michelin. But while the Michelin found five hundredths on average over the Goodyear, we’d stop short of saying it won the test.

Our control tyre also found speed throughout the day. It gained a tenth on its second run and then a hundredth on its third and final go. This tapering advantage was most likely dictated by the surface temperature, which jumped from 27.7 degrees Celsius in the morning to 36.9 degrees at midday but then only peaked at 39 degrees.

In the end, our formula only penalised one tyre after adjusting the results. The Goodyear put in a good enough performance on raw results alone, much earlier in the running order, to overtake Michelin once a weighted adjustment was applied.

04: Wet & Dry Braking

Few things stress a tyre’s importance more clearly than an emergency braking test. That’s not only because the results spew out the widest variation between best and worst in our field, but also because it’s easier to understand how the difference translates to the real world. Five metres here could hold the difference between avoiding or meeting disaster.

Ours involved seeing which tyre can stop in the shortest distance from 100km/h. It’s not far from the truth saying you or I might find ourselves trying this out unexpectedly behind a pile-up on the highway.

The method involved Luffy charging at a braking zone at 110km/h and then braking as hard as possible for a full ABS stop. This way we measured how well the car can stop from 100km/h, rather than the driver.

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The wet test, meanwhile, replicated our dry method. Instead, this time Luffy approached a section drenched under soaker hoses at 90km/h so the VBOX can record the distance it takes to stop from 80km/h.

Every tyre had three runs at each test, with the average of those stopping distances being counted.

Although the Michelin logged the shortest average distance in the dry, closely followed by the Yokohama, the control tyre performance improved considerably over the day. A combination of rising surface temperatures and increasing brake efficiency saw its distances fall from 38.91m at first to 37.77m and then finally 37.55m.

So, after feeding the results into our linear regression-based formula, the earlier run Goodyear emerged on top. The formula slashed just over one metre from its stopping distance. Meanwhile, the Yokohama and Michelin only improved by 0.3m and 0.1m respectively because they ran just before the last control tyre, which wasn’t enough to catch the Goodyear.

It was a similar story for the wet test. Rising temperatures and a slight breeze in the afternoon saw the control tyre performances improve as the day went on. However, this made no difference at all to the eventual winner, only second place. The Yokohama leapfrogged the Michelin into second after the formula set the results straight.

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MOTOR 2021 Tyre Test Winner: Goodyear Eagle F1 Supersport

To determine a winner, we’ve kept it as simple as possible. Each placing a tyre achieved is the score given to it for that discipline. Those scores are then tallied. Finally, the lowest score wins.

It was clear from the outset a dogfight was brewing between three patterns: the Goodyear Eagle F1 Supersport, Michelin Pilot Sport 4 S and Yokohama Advan Sport V105. They shared the top-three places in every discipline, except the Lateral G, where the Yokohama was downgraded to fourth after the results were adjusted.

Besides a strong wet braking test, the Yokohama primarily occupied third place – leaving the Michelin and Goodyear to duke it out for the win. But running the two premier patterns at opposite times of the day put a lot of power in the linear regression-based formula’s hands, as the Michelin’s top showings on raw data were never guaranteed.

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As it turned out, with the control tyre consistently improving towards the day’s end, the formula made the reigning champ Michelin relinquish the slalom and dry braking wins to the Goodyear. Add that to a convincing win in the wet even on raw data, and the event was sealed in the Goodyear’s favour.

Victory comes as redemption for the Goodyear, which fought hard in 2019 to finish second behind the Michelin. The improvement was unexpected, but the Goodyear faced the exact same settings as its competitors, so we can’t take anything away from a deserving win.

Down the order our bottom three found themselves locked in a battle similar as the top. The Pirelli P Zero, HiFly Challenger and GT Radial finished fourth, fifth and sixth respectively in most disciplines and placed in the order as such, completing the picture for the class of 2021. Bravo.

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The Hot Seat

Warren Luff, the ring master

With more than 20 individual exercises to run on each tyre, testing rubber is serious work – both on the mind and body. This is why we’re lucky to have someone of Warren Luff’s calibre behind the steering wheel.

Lending his services to MOTOR for more than a decade as the gun driver on most of our mega tests, whether they be to find the best performance car or tyre, he also finds himself regularly on the roster of Australia’s top motorsport firms.

A two-time Sandown 500 winner in 2012 and 2016, he’ll again be looking to add a Bathurst 1000 win to his multiple podiums at The Mountain this October for Walkinshaw Andretti United as co-driver alongside young gun Bryce Fullwood.

Even with this experience, he still admits tyre testing is one of the most physically demanding tasks he faces.

But this makes his consistent ability to get the most from each tyre – fundamental to a successful event – more astonishing. We’re lucky to have him.

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Hooray Tyreright

Our number one pit crew

A huge thanks goes to the crew at Tyreright.

As the operational bedrock of our tyre test and critical to a successful day, they kept our schedule ticking over as planned after handling the 36-plus tyre changes we needed without a flinch – all while only having the one set of wheels on the A45 S to work with.

Their high-end Mobile Tyre Fitment station based on a Ford Transit came decked out with professional gear from Eagle SMF, and it made us wonder if we’d ever need to travel to a tyre shop again when they can simply go to you.

Make sure you visit tyreright.com.au or phone 138 168 when shopping for your next set of tyres.

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