By Tony Hotland

Tires played a crucial role at last weekend's Malaysian Grand Prix, with poor choices sending world champions Ferrari out of the points, and astute ones landing underrated teams like Brawn GP and Toyota on the podium.

The time to pit and change to intermediate (previously called wet) or wet (previously extreme wet) tires have once again shown that a super getaway, like that by Nico Rosberg of Williams, could end up meaning nothing on a wet track. Especially when the rain threatens, then holds off, then pours as it did at Sepang.

The twilight race was called off after 32 out of the 56 scheduled laps, following torrential downpour and fading light. Rosberg had led in the first 15 laps, even posting a three-second lead, but finished eighth.

He pitted on lap 15 and came out fourth. Jarno Trulli, starting in second, followed a lap later along with Brawn GP driver and eventual winner Jenson Button, who had been trailing in third, and his teammate Rubens Barrichello.

"I really struggled with the rear end. But then I closed up on Jarno and Nico and knew I was going longer, and when they pitted I could put in a couple of quick laps. It got me in front and it was looking like it was going to be fine until I looked up and saw the clouds come over and it started raining," said Button.

And as the rain began spitting, Button went in for the full wets and it proved to be the wrong choice, as the expected downpour was not yet forthcoming.

He resumed still in the lead and continued that way until it became clear just how fast Toyota's Timo Glock, who had started in third, was going on intermediates after his stop on lap 22.

"A few other people made the correct choice, but we had a 16-18-second lead at that point. So I carried on and it started chewing itself up, so I pitted for inters as this guy *Timo* was flying. I came out just behind him, but my inter was obviously new and his was very old and I was able to get past him on the wetter part of the circuit just before he pitted. I got one good lap on the inter, but then it started chucking it down, so I came in for the full wet," he said.

Talking reporters through his experience with his inspirational choice of tires, Glock said it was "one of the best races I could ever do".

"After five or six laps I saw already the clouds were coming and I was asking 'when is the rain coming, when is the rain coming' and they said, you know it should come in the next couple of minutes, and then I thought it takes so long as you saw the big clouds coming definitely.

"It took just so long and we were so close to the first pit stop, so I said 'OK, I will take the risk and we will go for it and go to inters and then we will see.' I saw already Ferrari's Felipe Massa was on heavy wets quite early and I knew that will destroy the tires as well, so I said, *we go for it and take the risk' and in the end it paid off."

So Button swept back in on lap 29 for inters, and grabbed the lead again from Glock, who dived in at the end of lap 30 for wets and battled for second place with BMW Sauber's Nick Heidfeld.

Heidfeld, who went straight with full wets on his first and only pit stop, said it was "the right call... a bit lucky obviously" as he eventually finished second.

"It started to rain and as Jenson said, it was clear that it would rain heavily, so we went on the extra wets and as it was pretty dry still, I tried to preserve my tires, especially the rear tires and therefore at the beginning there were a couple of cars quicker than me.

"I was even overtaken by one guy, some people were driving away from me, but I knew they would kill their tires and if it would start drizzling or raining a bit more, I would then have the tire and I would be able to stay out."

Going on full wets early on, nevertheless proved to be premature and disastrous for Ferrari's Kimi Raikkonen, the 2007 world champion, who lapped more than 20 seconds slower than Button. He switched to wets four laps before the relatively light rain arrived. He ended 14th.

A similar fate greeted teammate Massa, who repeatedly found himself on the wrong rubber at the wrong time.

"With hindsight, it's clear we took some wrong decisions, especially in Kimi's case at his first pit stop," said Stefano Domenicali, Ferrari's director of sports management.

"The information we had at the time was that the storm was due to hit in a very short time, when in fact it took a few more minutes for the rain to come."

A wet tire works very differently from a dry tire.

"A dry compound's stickiness is similar to tank tape in the way the tire sticks to the road. But the way a wet compound works is more like starch... when you add water, it gets sticky," said Hirohide Hamashima, director of Bridgestone Motorsport Tire Development.

Bridgestone is currently the sole tire supplier for F1 races.

"In the final lap of the 2008 season, we saw the difference the wet tire can make when used in the correct conditions," Hamashima said.

"2008 World Champion Lewis Hamilton was using wet tires and he was able to lap much faster than Timo Glock on dry tires. The conditions clearly suited the wet tires, and because of this, Lewis was able to overtake Timo on the final corner." --THe Jakarta Post/Asia News Network