Was Mercedes really helped by the tyre change?

There's been a lot of talk about tyres so far in the 2018 Formula 1 season, but during the Spanish Grand Prix weekend a combination of Mercedes getting back on top and a change in the Pirelli tyre specification prompted even more of it.

Pirelli's decision to reduce the tyre gauge (the tread thickness) is something that can have a major influence on how tyres behave and warm up, and how they hold that heat. It's another learning curve for the teams, so the question is: did this help Mercedes, and why?

Reducing the gauge of the tyre is mainly to reduce the risk of the kind of blistering encountered during pre-season testing. It is the rubber content that retains the heat in the tyre, and once this reaches a critical level the rubber starts to form liquid pockets, like blistered skin. Even if it's not visible, you can still get internal blistering.

Sebastian Vettel suggested that the tyre compounds had got harder. This is because with a thinner gauge it really will feel like it is a harder compound, even if it's not. This is because there's less rubber moving around, so for some it will feel like there is less grip.

A thinner gauge will play into the hands of the teams with higher downforce levels since the tyre will be more stable, and because of the extra downforce the tyres will be worked harder - generating better and more controllable grip levels.

The thinner gauge will change the tyre stiffness, also because there's less rubber moving around. In turn, that will alter the response of the car when steering lock is applied.

As you turn the steering, first the front will respond faster - making the turn-in more precise. So if that is what your car needed to go faster, then fine. If it didn't, it makes the car too pointy and you need to work on the set up.

Lewis Hamilton talked about having confidence in the rear of the car in Spain that he had been lacking since the season-opening Australian Grand Prix. Well, confidence in the rear end is all about rear tyre response.

When a driver turns the steering wheel, the front tyre picks up the grip but you have to wait for the rear to get the message that it needs to pick up the lateral force. Initially it feels like the car is going to oversteer, but if that feeling goes away more or less immediately then you will have more confidence in the rear. So that could also have been a factor in why Hamilton felt so much better.

Even if you listen to everyone, your final decision would be swayed by the big boys

A thinner-gauge tyre should heat up more slowly, but it will not retain the heat so well. So basically it will cool down faster on the straights. Some would say that's exactly what the Pirelli tyre needs: faster warm-up and less retention of heat, but that was fine in the days when you had more testing available to try to understand the set-up changes required to get the best from any new tyre philosophy. It's harder to handle now.

Every car has its own inherent balance and there isn't much you can do about it. So some teams might just have lucked in with the right characteristics to reduce the inherent negatives. For others, it might have exaggerated their problems.

Way back when I was a boy, we went testing at Interlagos with John Watson in the McLaren M28. It was on the old long circuit with the long, flat-out left-hander at the end of the pit straight. John was flat through there, no problem (although he might not agree about the 'no problem' bit).

When we came back for the Brazilian Grand Prix, Goodyear had altered the tyres to compensate for the high-load ground effect cars such as the Lotus. Our car was a dog on those tyres and just couldn't work them.

Back in those days we knew very little about the tyres so we just had to get on with it. They are your only connection with the ground, so getting them to work correctly can give you a massive return in laptime.

There were all sorts of conspiracy theories being thrown around in Barcelona, but I'm sure Pirelli made this decision in a professional manner with input from all the teams. But I'm also sure that Pirelli would be steered just that little bit more by the team that has won the last four world championships. Even if you listen to everyone, your final decision would be swayed by the big boys.

In my days at Jordan using Bridgestone tyres, we got the kind of tyres Ferrari wanted. In a similar way, if Sauber had said during the discussions this year that it didn't want the thinner-gauge tyres, it would have made very little difference to the final decision.

It's not that unusual for changes like this to happen. Bridgestone used to play around with gauge thickness from race to race, but we were talking about 0.1mm difference on a rubber tread of roughly 3.5mm. So that was a small change, and even then it had a serious impact on how the cars worked the tyres.

Pirelli says it has reduced the gauge thickness by 0.4mm, which is a lot when you consider that the overall tread thickness won't be much different to the old Bridgestones. The change will have a significant effect on how the tyres come in to and stay in their working window.

But Pirelli did the right thing. It had concerns about blistering at a circuit that has been resurfaced and has got a lot faster. And excessive blistering can lead to a tyre failure.

Remember how much stick Pirelli got when tyres started exploding? I was probably one of the only people on its side at that time, and it can't put itself in line for that kind of abuse.

The tyre-gauge change has only been made for Barcelona, Paul Ricard and Silverstone, so if it did help Mercedes then things will be back to normal in Monaco.

Mercedes has been doing a lot of head-scratching this season and will probably go away from Spain with more questions than answers. It was very fast in pre-season testing, so as a team it has a really good handle on what makes the car perform at Barcelona. But after its inconsistent performances in the first four races, the thinner tyre gauges will probably have just created more confusion and questions.

I think the Mercedes has always been the best in terms of underlying performance, it's just that something has been getting in the way of getting the best from it. Williams has talked about its diffuser stall problem, Force India about the windtunnel correlation problem, but Mercedes won't show weakness by talking about problems like that even though it has been relatively open about its tyre troubles.

I'm not so sure Ferrari struggled with the tyre change so much as the cooler temperatures held it back. Vettel wasn't too far away in qualifying, but was way off the race pace when the track was cooler - a fraction under seven-tenths of a second per lap in the first stint.

This time last year, Ferrari's good race day performances were often because of looking after the tyres well. But in Spain, Vettel was the first to make a regular pitstop on lap 17 out of 66, and when you consider he started on the softs he should have been able to go further - into the 20s as far as laps are concerned.

Mercedes always has been the best in terms of underlying performance, it's just that something has been getting in the way

But you just have to look back at pre-season testing. Then, it seemed the season's result was a given. After losing the Australian GP, Hamilton's campaign went into a downward spiral that he only pulled out of in Spain.

But it's just one weekend, so let's see what happens in the next couple of races before drawing too many conclusions.

THE DEVELOPMENT WAR

Moving on from tyres, Spain is also traditionally an event where teams bring significant updates, making it an ideal time to look at their development progress.

While we didn't see any dramatic leaps at Barcelona last weekend, there are still signs of who's going in what direction compared with last year.

To make this assessment I've taken the team's fastest lap from each of the first five races as a percentage of the outright fastest and averaged it out. So if a team had been fastest in every race, its performance figure would be 100.000%. This figure, compared with the 2017 season, gives an idea of who is going in what direction, and the performance for the Spanish GP is also included.

If you compare that with the five-race average, you can see who is going in what direction even though the final result may be influenced by the Pirelli change.

Mercedes

Five-race average: 100.189%
Spanish GP: 100.000%
2017 season: 100.085%

Mercedes has made a small improvement to just nip ahead of Ferrari on average. Other than in Australia, where Hamilton's car was a rocketship, it's been nip and tuck between them all season and long may that continue.

The thinner tyre gauge will affect different cars in different ways, and Mercedes might just have got the short-term advantage from it. But Mercedes was very strong in pre-season testing in Barcelona, so the team definitely knows how to get the best from its car at this circuit.

Ferrari

Five-race average: 100.198%
Spanish GP: 100.173%
2017 season: 100.263%

Someone wise once said to me 'don't spend all your time trying to optimise the rear view mirrors, there is not enough return from that area of development'. Well, that's the biggest thing I could see on the Ferrari at Barcelona and it really hasn't moved anywhere worth talking about.

The big problem for me is that it seems to have lost that race-day tyre degradation advantage that it had last year. After throwing away good points in Baku, Ferrari has lost more at Barcelona and given up the lead in the constructors' championship to Mercedes.

Red Bull

Five-race average: 100.680%
Spanish GP: 100.844%
2017 season: 100.958%

Barcelona was a bit of a drop-off for Red Bull, which was a surprise because normally this track is where it really performs to its maximum. The numbers show it has gone backwards a little bit.

It introduced a new bargeboard package, and I have to say it's one of the most sophisticated in the pitlane, so it might take a little time to get on top of how it changes the requirements of the car set-up.

Given that Red Bull was actually fractionally more competitive at the back end of last season, it's clear there's some work to do.

Renault

Five-race average: 101.788%
Spanish GP: 102.123%
2017 season: 102.186%

Like Red Bull, Renault has fallen away a little bit from its overall average. It had a bit of a troubled weekend with Nico Hulkenberg having a fuel pick-up problem in qualifying and being caught up in a crash very early in the race, so perhaps the performance is actually better than we have seen so far after Renault introduced what it called a minor upgrade package with a modified front wing.

Monaco will be a good reference for Renault, since it's such low-speed track. The engine performance isn't quite as important as it is on a higher-speed track. But I feel Renault needs a development step pretty soon.

Haas

Five-race average: 101.939%
Spanish GP: 101.897%
2017 season: 102.858%

Haas is doing a good job at the moment and didn't bring much in the way of developments to Barcelona. Sometimes that's a good thing, since it allows you to concentrate on what you understand and get the best from an existing package.

Kevin Magnussen is showing that he has good speed, and while maybe he sometimes gets his elbows out a little more than he should that's better than being timid. As for Romain Grosjean, he seems to have stepped back a few years and has become a magnet for any trouble that he can find.

Force India

Five-race average: 102.365%
Spanish GP: 103.312%
2017 season: 102.199%

Force India is still struggling to get on top of things in 2018, and it is hard to see since it's a team close to my heart. Many of the guys and girls still there came out of the Jordan days, so they're people I know really well.

The car has an inherent aerodynamic problem, and when you encounter something like that it's important to do what you can to identify why that is. If you just keep throwing new parts at the car the problem can very easily just get worse, although the team does seem more confident it's now on the right path.

Barcelona is a demanding circuit on every area of the car and it has shown that it has work to do. Force India has the drive, but it will take time before it gets back to how it performed in both 2016/17 when it was fourth in the constructors' championship.

McLaren

Five-race average: 102.422%
Spanish GP: 102.032%
2017 season: 102.510%

Big things were expected from McLaren at Barcelona, but it didn't really go that way. Yes, as the numbers suggested, it has moved forward by something like 0.4% compared with the average. But consider that this improvement probably cost around £2million to achieve - and that's just the hardware, not the research and development that it required to push the button on making the parts.

More will come from the package, but as Fernando Alonso says it is still a lifetime away from the frontrunners. McLaren needs to set its vision on what Red Bull and, on the odd occasion, what Renault can do. Overhauling them is the next target and only then can it look beyond that.

Toro Rosso

Five-race average: 102.926%
Spanish GP: 103.006%
2017 season: 102.730%

The best way of summing up Toro Rosso's performance is that it needs a bit of luck. Again, if there is something happening its cars seem to be in the middle of it - I suppose that is what being in the middle of the pack brings.

The car has shown that it has the potential to be in there as best of the rest as it was in Bahrain, but it all seems to go wrong at the crucial moment.

But you wouldn't really say that the Honda power unit's performance is holding it back dramatically. Perhaps there is a bit missing but I'm pretty sure that Honda is now on a development glidepath that will reap rewards before the end of the season.

Yes, there may be a few grid penalties on the way, but that is no bad thing if in the end it gets you to where you want to go in the long term.

Sauber

Five-race average: 103.377%
Spanish GP: 103.266%
2017 season: 104.129%

Sauber is still hanging in there on speed and points, and has moved ahead of Williams. But under the surface it is making more progress than it has shown.

The relationship with Ferrari will mature as the season goes on, so having started the year as probably the smallest team in F1 it will be able to build on that. With Alfa Romeo branding, Sauber can look forwards with confidence that it has the budget to continue into the future. It had quite a few years without that luxury.

Charles Leclerc is a huge asset for Sauber, and in driving as he did at Barcelona when he was racing the old maestro Alonso and Carlos Sainz Jr really showed his true talent and his understanding of the big picture.

Williams

Five-race average: 103.529%
Spanish GP: 104.624%
2017 season: 102.526%

It looks like the upturn in the Williams performance in Baku was a bit of a freak occurrence, and that the circuit requirements had something to do with it. In Baku there are no long corners, so consistent balance is not as important as it is at Barcelona.

As a team, with the technical leadership it has in place, Williams should be able to get on top of the problems quickly. That's not what I'm seeing.

Something is not right there in how the circuit performance and the hunger for success is dished out. Williams has slowly gone backwards since finishing third in the constructors' championship in 2014 - that's four years of a slide in the wrong direction and it's time for someone to put a stop to it.

Overall, there are a few teams that need to start to dig deep. Red Bull, Force India and Williams are probably the three that I would say are starting to face some internal pressure, with McLaren not far behind.

But it looks like the leviathan that is Mercedes has now found its feet. It will be interesting to see where Ferrari stands in Monaco, as last year the slower circuits were its forte. But it has joined the Mercedes club and lengthened its wheelbase for 2018 so I wonder if it will have lost that asset on the slower circuits? If it has, then the rest of the season could become a bit more of a procession.