Tyre test 2008: Test 4 - Wet slalom

Wheels Tyre Test 2008: Tyre Test 4 - Wet slalom

Wheels Magazine
June, 2008

WHAT WE MEASURED & HOW
The wet slalom is exactly like the dry slalom, only we added water. The wet and dry tests were performed on consecutive days (wet first, since the heavens threatened to open all day long on day one) but the track set-up remained constant, right down to the precise positions of each of the cones and the timing beams.

Procedurally, both events were identical, except the running order of the tyres was altered, both for convenience in the fitting bay, and to keep the driver in the dark about which tyre was on each car, when.

Eastern Creek's skid pan is challenged for length, so we ran the slalom diagonally. In order to engineer enough run-off area at the distant end, the slalom had to start in the dry, which at least afforded a consistent launch. Just after the first cone there's a slight dip that collects the water from the irrigation system and channels it off for recycling. After the splash in the dip, it's all consistently wet.

SLALOMING: WET v DRY
When you look at the 235/45R17 results in tests three and four - the slalom tests - a few pretty obvious facts emerge.

First up, the same tyres keep featuring at either end of the pack, with some slight variation. Good in the wet generally means good in the dry, and the poorer performers remain comparatively poor no matter whether it's wet or dry.

Second, the best tyres appear not to trade off very much cornering performance when dry conditions turn wet. The Falken FK 452 took first place in both the wet and the dry, with the margin just 0.1 seconds - that's 1.4 percent slower, or 3.5 percent less cornering grip, depending on how your mind works.

The popular Bridgestone Turanza ER300, on the other hand, wooden-spooned both slalom events. But when dry turned wet it lost 0.36 seconds (becoming five percent slower than its own dry performance), which also means 10 percent less cornering grip.

It gets worse. The split between best and worst in the dry is a lot less than that in the wet - poorer tyres appear to get worse in the wet. The split between the Falken in first and the Bridgestone in last in the dry was 0.18 seconds (2.5 percent) in speed and 5.2 percent in grip. In the wet, the margin jumped to 0.44 seconds (6.2 percent) in speed and 12.8 percent in grip.

It's worth remembering at this point that the Falken and the Goodyear have been in the top three spots in all four cornering tests, and the Turanza ER300 has come last in all four - albeit by narrow margins in some cases.

"GIMME A G!"
Start talking cornering and the chat will eventually turn to Gs, about which there's a fair old degree of disinformation. G stands for 'gravity', which is more or less constant, depending on whether you like Mr Newton's or Mr Einstein's version of events. One G is the acceleration of an object free-falling on earth, in the absence of aerodynamic drag.

One G is also a force - the force gravity imposes on you, through your feet, and which the floor resists.

Pulling one G in cornering shoves you sideways in the car with an inertial load equal to the pull of gravity (in reality, it's the car that's accelerating the other way, into you.) Good road cars get close to one G and race cars routinely exceed it. F1 cars pull as much as six G.

☆ WINNER: 235/45R17 - Falken FK 452
With all four cornering-based tests wrapped up, the Falken and the Goodyear Eagle F1 Asymmetric will have to drop the ball badly not to end up looking pretty darn good by the close of play. The Falken first-placed the slalom both wet and dry, and took second in both outright cornering tests, with the Goodyear virtually reversing that trend. Surprisingly - for a brand we'd never seen before the test kicked off - the Accelera proved itself quite capable in the wet, with second spot in the wet slalom complementing its third in the wet cornering test.

Intro:   Let's roll ...	Test 5: Dry braking ...
Test 1: Dry cornering ...	Test 6: Wet braking ...
Test 2: Wet cornering ...	Test 7: Hot lap & summary ...
Test 3: Dry slalom ...

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