tyre temperature - the only thing that matters

[dave kumar]

Tyre performance is the single biggest contributor to lap time. There I said it, might be wrong but I'm for one quite glad we no longer have more than one supplier to the teams. I mean who wants to tune in to just find out whether bridgestone or michelin are going to make better compounds this year, wow.

OK so if we accept that tyres are quite important , would the best F1 car be the car that can easily be changed to suit track conditions and get its tyres to the desired temp? Am I conflating tyre temperature and tyre performance? Rob Smedley said in the post race interview smooze that the improvement of the Ferrari in the race as compared to qualifying was all down to getting a bit more heat in to the tyres on race day. 'What are we talking about here, a few degrees...' (DC) 'yes a couple of degrees makes all the difference' (RS). OK that bit was paraphrased but I remember the discussion. Rob Smedley also mentioned the aggressive slip angle they 'need' to run on the Ferrari to generate grip but I don't know if this is a design choice or a necessity.

but wait a minute... what about the drivers. They must have some influence on tyre temp. Are the best drivers those that can modify their style to manage their tyres? We all laughed at Richard Hammond (Top Gear BBC for those that aren't lucky enough to see this glorious waste of the licence fee) when he couldn't get the R25 to go round the corners because he wasn't driving the car fast enough to get the tyres up to temp. Its a vicious circle, not enough tyre temp->no grip->no speed->no tyre temp. Are all F1 drivers on this knife edge only the margins are so small that we can't appreciate it from our comfy armchairs?

If tyre temperature is the only thing that matters, then is a designer's focus about making a car that can be easily tuned to track conditions or do they just make it and let the trackside engineers worry about dialing the car in to the track (hopefully that means what I think it means [-o< ).

[qw56q]

yes but the faster they warm the tire the faster it will wear,though this could be used to put more qualifying laps down.

[Jersey Tom]

Tire temp isn't the only thing that matters.

And people seem to have this notion in their head that "more heat = more grip." Just not true, or at least not that simple.

Also, don't take everything the drivers say as fact.

[dave kumar]

Well I wasn't suggesting that more heat always results in more grip. Hey otherwise they'd just set fire to the tyres and let rip. I want to know if maintaining the tyres at optimal temperature is critical to grip, as Rob Smedley suggested there is a sharp drop off in performance just a few degrees either side of this critical temperature.

[Belatti]

Well I wasn't suggesting that more heat always results in more grip. Hey otherwise they'd just set fire to the tyres and let rip. I want to know if maintaining the tyres at optimal temperature is critical to grip, as Rob Smedley suggested there is a sharp drop off in performance just a few degrees either side of this critical temperature.

Nie question!

I have my eyes prepared like a couple of fried eggs... and eager to read now!

Tom, c´mon tire guy! Be more specific!!!

[ESPImperium]

I think you have it in one there.

But there is a vicious other side, that i think red bull have seen this year and that is that if the car design is creating too much heat this can lead to the tyres waring out too fast. See what happend to Vettel at Melbourne and Monaco where he binned the car both times, once with the aid of Kubica.

But i think there is a fine line, yes. And getting in that "zone" that is close to that zone as posible, i think that its gonna help your car alot. Id say if youre about 1 or 2 oC on the cold side and it its about 4 or 5 oC on the hotter side id say that it could be fine, but all depend on the track that weekend.

Hotter side cars will work well in the rain and the cooler tracks as those cars can generate the heat to stick to the track. Im thinking the red Bull RB5 is this seasons example of this. But this type of car tends to wear out its tyres quicker.

Colder side cars do well in warmer tracks as they can endure the heat better and get the longevity out of the tyre so that strategy can play a massive part in the race for that car. Im thinking the Brawn BGP001 is the car of choice here.

Tyres are the other constant that a designer can work with in F1, but i feel that this year the designers have forgotten how propper slicks worh this year, after all those years in the wilderness with grooves. I think that teams have seen this with the mechanical impact side of things, taking the Renault Drive Shaft Boot problems that the RB5 experienced. But i think that the teams are now starting to make in-roads into the tyre temprature problem, that is so crucial to lap-time.

[Jersey Tom]

Since ya asked, Belatti:

I highly doubt that any team (or tire manufacturer) truly knows their "optimum" temperature point of their tires. The whole concept is kind of a crock if you ask me. There's no such thing as having a "optimized" car, much less tire, much less tire temp. Way too much stuff that's just open to interpretation or you can't always put a hard number to. F1 is not magic. They certainly improve their cars at a rapid pace, but there's never anything "optimum" that I can think of. That's why engineers get paid good money for their judgment, and race results can change dramatically every week.

Let's say you're looking for "optimum" tire temp... what kind of temperature, at the surface or at the belts? at what load (always changing)? At what sliding velocity (always changing)? On what surface (not a constant)? After how much heat history (constantly increasing)? After how much strain softening (constantly increasing)? There's too much to possibly be able to characterize. At best you might know some nebulous range (which you will generally get from a manufacturer), and even that's a challenge.

How do you even measure tire temperature accurately within a couple degrees at the racetrack? You don't. IR temperatures have drift errors over time, and temperature compensation errors. The reflectivity and 'sheen' of the tire changes as it gets hot, which will change how some IR sensors read. Needle pyrometer readings can be very inconsistent as well. Two people could be on the same tire with the same pyrometer and get values different by up to 30F just by a difference in feel.

How would you know if a couple degrees difference in ambient temp, which then lead to a tire temp change.. really affected the tires or something else? Aero performance changes with ambient temperature (significantly). Engine performance changes with ambient temperature (significantly).

For that matter, I think designing a car to make the tires run hotter or colder (globally, not on one axle) is also a crock. I could be wrong. How would you do it? Scrub radius does nothing, nor mechanical trail. I'm skeptical if dynamic "scrub" really does anything. You can probably do some with static toe.. but then you're also messing with the ultimate sideslip angle your car gets to (potential big aero impact), slip angle drag, blah blah blah. How do you really know what is doing what? Biggest things that will change temp the most are load, speed, and slip. The DRIVER controls all of those. Gotta drive fast to work the tires and get the heat up.

Bottom line is, lots of people make a big to-do about tire temp, but it's almost all hand waving from what I see. You can make up a lot of track time with temperature distribution, but even that can be misleading at times.

[sticky667]

Tyres are the other constant that a designer can work with in F1, but i feel that this year the designers have forgotten how propper slicks worh this year, after all those years in the wilderness with grooves. I think that teams have seen this with the mechanical impact side of things, taking the Renault Drive Shaft Boot problems that the RB5 experienced. But i think that the teams are now starting to make in-roads into the tyre temprature problem, that is so crucial to lap-time.

I think this is a direct correlation to the ban on testing. This is been an interesting engineering feat this year for the designers and the teams. The past 12 yrs have been a free for all for many designs ideas and changes at a whim's notice. Suddenly they are forced back to the drawing board and need to measure twice and cut once.

Hopefully with the 2009 regs being constant we will be able to continue to see the progress made by the teams for 2010 without the radical changes. (besides the refueling ban)

[Jersey Tom]

Another item I forgot to point out earlier... grip isn't everything (if you did magically have a number for temp to get highest grip, and you could tune your car to get to it).

There have been times with a racecar testing two tire sets.. A and B. A is the control tire. B is softer, with more grip. Car runs faster laps on tire A!

And it's not because of wear, graining, or rolling resistance. Professional, talented driver as well. We'll see who figures out why...

[Conceptual]

Tom,

If there is no optimim for the tyres, why was the Tyre War such a big deal?

From everything I have read, tyre temp on a race car cannot be taken out of the context of the rest of the car. It is not as much a variable to control, but more like a multiplier to all variables. On track, a car is seldom (if ever) in a static state, so like Tom said, there can not really be a single optimum, but a range over the length of the track.

I notice this is race sims. If you take the tyre temps at any given point on a track, it is directly balanced to the corner that was just completed. If you do not get a well balanced left/right track, sometimes you need an asymetrical setup to compensate for the lack of even cycling. IE: If there are 3 less right turns than left (or longer turns left than right), I have found that small offsets in camber/castor/toe/springs/damper/ride height/rollbar can be used to get the same temps at all 4 wheels over the lap, but very seldom do they wear evenly left to right during the course of the lap, so the optimum would depend on too many changes in state to be a hard number.

Still open to some more education from any tyre engineers out there!

[WhiteBlue]

Bridgestone are deliberately allowed to make it hard for the race engineers to prepare for each tyre choice. You could say with a degree of confidence that the system is set up to make it difficult for the race engineers. If it was easy Bridgestone would have no tyre talk and get no exposure.

[dave kumar]

Let's say you're looking for "optimum" tire temp... what kind of temperature, at the surface or at the belts? at what load (always changing)? At what sliding velocity (always changing)? On what surface (not a constant)? After how much heat history (constantly increasing)? After how much strain softening (constantly increasing)? There's too much to possibly be able to characterize. At best you might know some nebulous range (which you will generally get from a manufacturer), and even that's a challenge.

Could tyre temperature just be a convenient hook to hang all these concepts on. I believe you when you say they can't measure any of these variables accurately, so the engineers must rely on the drivers for feedback on how the tyres are performing and maybe that's the kind of thing the driver says - 'gee I just couldn't get enough heat in to the front tyres' and the engineer looks back at him and sighs 'there's no such thing as heat... its thermal energy transfer'.

OK, there isn't an optimum temperature but instead a way of working the tyre, so that you get the best performance for the number of laps desired (just a qualifying lap or a long stint during the race). In this scenario the Red Bull cars are working their tyres harder - more side slip, greater load, who knows... and the Brawns aren't as hard on the tyres, hence better tyre longevity but with the greater risk of failing to get the tyres to perform in the first place.

But is it really about the cars or is it the drivers who are responsible for managing the tyres. Barrichello wasn't affected the way Button was on a cold (sorry, old habits) circuit - same car different driving styles. Same could be said of Vetel and Webber at Monaco.

[Jersey Tom]

If there is no optimim for the tyres, why was the Tyre War such a big deal?

"Optimum" tire temperatures, and a tire war, are two very separate topics.

OK, there isn't an optimum temperature but instead a way of working the tyre, so that you get the best performance for the number of laps desired (just a qualifying lap or a long stint during the race).

Precisely.

[Ian P.]

Bridgestone are deliberately allowed to make it hard for the race engineers to prepare for each tyre choice. You could say with a degree of confidence that the system is set up to make it difficult for the race engineers. If it was easy Bridgestone would have no tyre talk and get no exposure.

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This year (2009) is incredibly unique. No tyre wars and no testing. Not only that, Bridgstone has the opportunity to choose tyre compounds that can and will favor certain teams over others. Not saying they will or have done, but the outcome of the championship is likely going to be influenced by the temperatures at the last few races and the ability of the teams to adapt to conditions and to the compounds that Bridgstone brings to the tracks.
Look for BGP to be working furiously at getting more heat into their tyres.

[Jersey Tom]

Not only that, Bridgstone has the opportunity to choose tyre compounds that can and will favor certain teams over others.

Uh, no. Or at least, how do you figure this. What are you basing this on.