Special insight: What happens to F1 tyres under load
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MTS Systems
Posted By: James Allen  |  23 Mar 2014   |  10:35 am GMT  |  60 comments

Picture an F1 car standing still in the pit lane. The sidewalls of the tyre are nice and straight and the contact patch of the tyre is touching the ground. But imagine what that tyre looks like when loaded up in a high speed corner – it flexes and the shape is no longer that ideal vertical line, so easy to model in a wind tunnel.


In modern F1 there is a real premium on understanding this phenomenon and being able to work with the changing shape of the tyre so that the car’s aerodynamics are the best they can be at all times.

In simple terms there is lap time to be gained from doing better in this area; so there’s a lot of work going on there at the moment.

For F1 fans looking to get insights into some of the more fascinating reaches of the sport, we’ve presented this special insight into a key innovation of today from one of our team who has an intimate knowledge of the problem, to find solutions for the F1 teams.

JA on F1 technical adviser Prof Mark Gillan was formerly chief operations engineer at Williams, Toyota and Jaguar and he recently gave a lecture on this subject as principal R&D engineer of MTS Systems, which makes testing equipment.

Tyre Testing and Impact of Deformation on Aerodynamics


Background to the problem:

In F1 and motorsports in general the tyres are the most important performance item on car. The tyres tend to have a relatively narrow optimal operating window, so loads and running pressures and temperatures must be controlled and monitored as well as possible. Wear, graining, blistering, degradation, durability, surface roughness, pick-up, inter/wet impact, are terms you hear all the time in commentary of F1 races and are all issues to be considered. With this in mind accurate modeling of this complex transient system is fundamental to ultimate performance, but all Teams are missing key elements to the puzzle (and so is the tyre manufacturer).

In F1 the tyre shape can have a significant impact on the car’s aerodynamic performance. Knowledge of the profile and contact patch shape is therefore vital to ensure that the key flow structures are in their correct places. In order to ensure good correlation in the development process the Computational Fluid Dynamics (CFD) virtual tyre and the wind-tunnel 50 or 60% scale model tyres must be accurate representations of the full-scale tyres, with the correct shape profile and contact patch throughout the entire operating envelope.

The image below (of a Michelin F1 tyre circa 2004) gives one a good indication of the complex shape the side wall deflects to under load. The Pirelli shape will be very similar.

The Teams have a number of tools at their disposal to ensure good correlation and they tend to use a mixture of virtual modelling, model scale testing, whole/part car multi-post rig testing and on track testing to improve their understanding of the car’s performance.

The motorsports tyre manufacturers will use, amongst other equipment, a tyre test-rig similar to the MTS Flat-Trac™ system. To control costs the F1 teams are restricted in the Technical Regulations (see below) from using these machines to extract certain force and moment data but the tyre manufacturer Pirelli can use them.

The most advanced system is currently the electric motor driven MTS Flat-Trac™ LTRe which is installed at SoVA Motion in the USA http://sovamotion.com This machine can simulate speeds of up to 200 mph (320kph) and simulate forces of up to 30,000N.

This video gives an indication of the amount of tyre deflection possible during extreme manoeuvres. If you stop the video at about 20 seconds you can see a good correlation between the side wall deflection on the Michelin F1 tyre in the image above and the motorsports tyre under investigation.

The key to it then, is to learn from this and to match the tyres’ full scale true loaded shapes to the virtual CFD tyre and wind-tunnel tyre shapes, otherwise a significant amount of CFD and wind-tunnel development runs will be wasted as they will not correlate to the real life conditions. And as F1 teams are now limited to only 30 hours a week for both, that’s a big problem.

This is the work that is going on behind the scenes today; the push to match the tyre shape and improve correlation is one part of the technology innovation that is taking place in motorsports and within F1 in particular. With the recent reductions in both wind-tunnel and CFD usage F1 teams need to continue to ensure that any testing is both efficient and correlates well to the track.

Tyres and in particular tyre shape and optimal aerodynamics are inextricably linked.

* FIA F1 2014 Sporting Regulations
25.5 Testing of tyres :
a) Tyres supplied to any competitor at any time may not be used on any rig or vehicle (other than an F1 car on an F1 approved track, at the exclusion of any kind of road simulator), either Team owned or rented, providing measurements of forces and/or moments produced by a rotating full size F1 tyre, other than uniquely vertical forces, tyre rolling resistance and aerodynamic drag.

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60 Comments
  1. neilmurg says:

    Is this part of the reason that F1 haven’t gone to more ‘road representative’ low profile tyres? That the uncertainty in the tyre performance and aerodynamics provides an area where the teams can compete on talent and not raw processing/analytical power.

    1. BobbyT says:

      My understanding is that the current 13 inch tyres properties form a significant part of the overall suspension requirements for the car and a change to low profile tyres would see teams have to radically alter their suspension componentry to cope with the changes. With teams trying to reduce costs it seems like an unnecessary change.

      1. Andrew Carter says:

        I think it’s more of a case that they don’t want to make the change for the sake of it rather than cost.

      2. Random 79 says:

        You’re right, but they’ve been talking about introducing low profile tyres for a while now, so I’m guessing that in the next big regulation change that will likely come along in five or six years time the switch low profile tyres will be a part of it.

      3. Gaz Boy says:

        Low profile tyres in F1? No, no, no!
        Personally, I’ve never liked them on road cars: and so does Jezza and Captain Slow too, both have complained that suspension compliance is virtually non existent on a tyre with virtually no sidewall. We all think ride comfort is not important in an F1 chassis, but think about it – would you want to race a car if you emerged from your car at the end of the race with a smashed skeleton, your knees crumbled to dust and blood pouring out of your ears?
        Does that sound an embellishment? Could be reality if F1 adopts the low profile monster!

      4. Random 79 says:

        You’ll notice that I didn’t say that it would be a good thing, just that it might happen.

      5. Gaz Boy says:

        RE Random: Yes, I know you were just speculating. Low profile tyres are the bane of the human spine and that’s in normal road cars. On a grand prix car generating 5G through Silverstone or Suzuka, the ride would be unbearable!

      6. shortsighted says:

        I am all for F1 switching to low profile tires to be more closer those used in road cars. Forcing F1 to develop a suspension system that can filter to road cars is a good thing. The tires and the suspension system used in F1 today have no correlation to modern day road cars. If the low profile tires does not absorb the F1 drivers well from road bumps, I am sure F1 designers can always think of something that can do so like softer driver seats, etc.

  2. kenneth chapman says:

    regarding the sporting regulations covering this subject i have one question…..why? surely the use of these rigs would enable teams to not only better understand tyre dynamics but would also add substantially more to the safety aspect.

    more and more restrictions on the pinnacle of motor sport.

    1. Steve Zodiac says:

      Totally agree, how can F1 truly be at the pinnacle with restrictions like this, They are all basically half developed and nowhere near as good or safe or fast as they could be (and more fuel efficient perhaps without having to lug loads of environmentaly un green batteries around)

      1. Quercus says:

        Given that ERS has reduced fuel consumption from 150Kg down to 100Kg per race, “lug loads of environmentaly un green batteries around” seems a rather distorted and somewhat ideological statement.

      2. Random 79 says:

        Nowhere near as good or fast: Arguably, especially the former, although their speed now is already not too far off what they were last year.

        But nowhere near as safe? Unless I’m completely misunderstanding you the cars are light years safer than they used to be – for proof of that you only have to have to look at some of the huge accidents that have occurred in recent years only to have the driver walk away without a scratch.

      3. Gaz Boy says:

        Very good point about safety Random.
        10 years ago Ralfie had a chat with the wall at Indy, and although he chipped his spine, and spent the summer at home in Austria, within a couple of months he was back racing, and finished 2nd at Suzuka.
        Also, Kubica (I my opinion the great lost talent to F1, although he has to take some of the blame for that himself) had that massive shunt at Montreal, couple of races he was back.
        Progress is a comfortable disease, and it has been for safety in F1, but at least it’s got there. 40 years this year, Helmuth Koinigg had a puncture at the US Grand Prix, crashed, and was be-headed by the an in correctly assembled barrier.
        Do we want to see drivers decapitated, or badly mutilated? No, of course not. Also, in the early 70s, drivers such as Piers Courage, Pedro Rodriquez, Jo Siffert and Roger Williamson all died in accidents from inhaling poisonous fumes from a fiery crash (Roger and Jo were not even burnt, and didn’t have a single broken bone). Thank goodness accidents involving fire are incredibly rare.
        Like I said, progress come slowly – but it has come.

      4. Gaz Boy says:

        PS in 1970 three grand prix drivers died in just five months – that was the brutal, ugly side of racing when safety was non existent.

    2. j says:

      Think about your question again. “Surely the use of these rigs would enable SOME teams (the ones with tons of money to burn) to better understand tyre dynamics”.

      And I wish the word “safety” wasn’t hastily tacked on to add weight and gravitas to some people’s opinions and arguments.

  3. james encore says:

    I find those rigs interesting (and wonder how the data collected is policed – e.g how would you catch a team running CFD models on a sponsors computers ? ). Once upon a time teams would have taken cars and gone off testing. They could build two wings, put them on cars drive round and round and decide what really worked. Now they must turn up at race with something which all the models tell them will work. It certainly hadn’t occurred to me that change in shape of tyre under load makes a difference between the model giving the right answer or not.
    Teams still raise all the money they can and spend it, but on simulators of all sorts to produce models to compensate for not being able to test enough on real cars. Very expensive kit whose return on investment is kept down by regulations. This is what the sport does in the name of “cost reduction”.

    1. Kramgp says:

      Well said . I would like to see more testing. Peter Windsor made a good point in F1 Racing he said F1 needs to be a year round show not just race weekends. More on track testing with young drivers and world champs would add to the show where multi confusing rigs just can’t.

    2. Andrew Carter says:

      How is hiring an extra 50 people for a specialised test team and then throwing endless bits at a car to find the handful that actually work cost effective, or anything other than needlessly wasteful? Also, since the end of the 90′s F1 has been moving consistently more towards relying on simulation technology, the testing ban just sped up the process of what was going to happen anyway. As for CFD, you can’t run these models on your average MAC or PC, the teams all have banks of super computers for the processing power to run this simulations, not something that Marlboro or Martini are just going to happen to have lying around.

      I do agree with you on the problem of young drivers getting seat time. Kvyat and Magnussen might have had excellent debut’s but I think they might be a bit special and still have mistakes ahead of them. However, their is increased testing this year, so we’ll see how much that helps things.

      1. james encore says:

        Well, Ferrari have (or had) AMD as sponsor, Renault have a Microsoft division as a sponsor, HP are sponsors. All big IT companies with High Performance Computing Clusters on tap. Every oil company has HPC resources; so any team sponsored by an oil company. In a past job I had some dealings with the HPC system for EADS who are a Caterham sponsor …

        If a team isn’t allowed to have 50 people for a test team + the resources that team uses they will have 50 people working in a wind tunnel, or 50 people working on CFD or 50 people working on test rigs. (or whatever combination). A team will always raise as much money as it can, and spend it.
        As Mark points out in the other reply, it’s impossible to stop the teams raising and spending money. So the FIA just diverts the spending from one thing to the next. I’m not sure that any way of letting the teams spend money is better or worse than any other.

      2. Andrew Carter says:

        I think I missed the point of your original post and took it as yet another person attacking the rules because of an all too simplistic view of the sport. As it is most of what I said doesnt apply to your post (Do’h!) but I will say that all the technology companies you pointed out are minor sponsors who would have no reason to spend the extra money on computing for such a small return on logo space.

        I don’t agree with you on the “return on investment” bit. It can be argued that the simulation tools are the most important tools available in developing an F1 car now, and regulated or not that makes their return on investment quite high, if the team can make best use of them.

      3. james encore says:

        I’m not talking about those companies buying something specifically for the teams, but the really about the difficulty of policing it. EADS (for example) might not write a very big cheque to Caterham, but have got HPC clusters which people outside the industry would find mind boggling. Shell probably write a much bigger cheque to Ferrari and what they have for simulating things in the seismic area for oil exploration is probably just as mind boggling to the layman. I suspect if most of the teams wanted to run some CFD models which needed more computing resource than the rules allow, they have people who could run them and it would be close to impossible to catch. Teams invest in HPC clusters, or Wind Tunnels but can only run them for a certain number of hours per week; so if you think of ROI in terms of hours of use per £ spent, its constrained. But yes you could look at it the other way and say if a simulation leads to a car scoring a couple of extra points then the prize money might amount to a good return.

    3. Mark Houston says:

      Everyone replying on this page seems to be against specific restrictions on specific things. This could all be solved if the FIA could get the teams to agree on a maximum budget restriction (and a way to police it), then the teams could go back to spending their budgets on what ever they wanted (even testing). However until that day all the FIA can do is to work out what the top teams are spending vast amounts on and then restrict that then wait until the re-direct their funds to something else and then repeat. Blame the teams on this one.

  4. CC says:

    Amazing to think that as recently as 30 years ago [sic], for the 1984 F1 season Goodyear was still supplying tyres that were made from cross ply construction. They must have been very inconsistent, perhaps that’s why the Michelin teams of McLaren and Brabham dominated the 1984 F1 season with their radial tyres – much better aerodynamic performance can be generated with a radial.
    I always thought the Michelin tyres during the 2004-2005 season had a sidewall that was marginal. The Michelin construction was a very soft sidewall with a very stiff tread pattern. Bridgestone were the exact opposite – a very stiff sidewall allied to a softer tread-block, which worked superbly well for Ferrari during the 2004 F1 season with the emphasis on very short stints and very light fuel loads. I remember the 2004 Indy and 2004 Belgian GP’s the Michelin users suffered extreme blow-outs from over-heating sidewalls (Alonso in 2004 Indy springs to mind), and yet the Bridgestone runners were hardly affected. And of course, there was 2005 Indy – Michelin obviously hadn’t learned the lessons of the previous season, and ultimately that led to a chain of events that saw Michelin having to withdraw from F1.
    I wonder if the ultra soft sidewall of the Michelin tyre during the 2005 F1 season (when tyre stops were banned) gave them the advantage over the more conservative sidewalled Bridgestone during that season – it certainly would have been a contributing factor.

    1. Andrew Carter says:

      The sidewall stiffness was a product of how the two tyres generated their grip. Bridgestone relied heavily on mechanical grip, with the soft tread block moving around, heating up and “grabbing onto” the track surface, which required a stiff sidewall for support.

      Michelin relied more on chemical bonding for their grip, though I can’t remember the reason for the softer sidewall. Interestingly for 2006 the two tyre characteristics began to converge.

    2. David Hamilton says:

      It always surprised me how Crossply tyres remained in F1 long after they had become obsolete on road cars.

      This article has gone a good way in explaining why that was the case – that the complex dynamics of F1 made a radical change of construction difficult to pull off and inherently risky.

      However Crossplys made for a fantastic spectacle – they give up the contact grip much more progressively on the limit than Radials, meaning that drivers were able to slide their cars around much much more in the 70s than they can do today.

      While the snappy handling on the limit at the Ozzie GP was entertaining, I still think that, from an audience perspective, Crossplys would be even more fun to watch.

  5. Richard in Aus says:

    I think this is an area that FOM TV could improve on greatly for the viewers at home. We often hear Martin say in the telecast that around 50 per cent of the car’s suspension is in the tyres. Yet FOM TV don’t put any cameras down there so the viewers can see this type of deflection on the coverage.

    Even the local touring cars here have this type of camera, so surely F1 can manage something similar. (Only thing I can think of is maybe the teams wouldn’t like a camera down there because it would disrupt the aero).

    https://www.youtube.com/watch?v=UTocyZ-kMss

    1. Michael in Seattle says:

      Thank you for the video link. Mesmerizing! Agree with you – FOM should provide this camera angle.

  6. aveli says:

    hello james, i think i have an idea how busy you are and how much you’re keen for us to have an improved f1 experience but it doesn’t take much effort to see that the tyre being tested doesn’t look like an f1 tyre.
    i doubt that rig in the video has anything to do with f1. f1 tyres have a much higher profile and are more likely to deform but as we all see on our television, the deformation is neither that extreme or obvious. it’s subtle and as you correctly stated, has a profound effect on the aerodynamics of the cars.

    1. Mark Gillan says:

      For sure the video is not of an F1 tyre but of another motorsports tyre. Unfortunately for confidentiality reasons I can’t show you a F1 tyre being tested on this machine, but these machines are used for all top level motor sports including F1, LMP, NASCAR, etc.

      I can assure you, having spent over 15 years dealing with the correlation issues that are created by tyre movement, that the side walls of a F1 tyre move a significant amount under dynamic load i.e. + 50mm.

      1. Bart says:

        Wow, Mark Gillan’s reply! Thanks a lot for the great insights you’ve been sharing with us! And a big thank you to James again. Cheers, Bart

      2. aveli says:

        thanks for your response mark and thanks to james for giving us mark’s contributions, it’d be great to have a glimpse of an f1 tyre on that rig even if it was one from previous seasons. i believe everything in your response but we all know that f1 tyres have taller and stiffer side walls than other motor sports tyres. last season we saw numerous punctures where the tyres disintegrated leaving just the side walls and they supported the loads from the car with ease into the pits. 50mm deflections as you report is more like it. in the video the deflections are over 100mm and not representative of f1. f1 is just that more exciting and i watched that video with keen eyes,anticipation, to see closely how an f1 tyre behaves under loads of different kinds. i hope you understand why i was disappointed or frustrated with that video. it’s not all bad by the way. please keep it coming.
        incidentally, is it possible to show us images of each drivers steering wheel

    2. Pat M says:

      I think I see several tires being tested in the video, and it looks like we actually get a glimpse of an F1 tire right at the beginning for a second or two (but I could be wrong).
      In his defense, James does describe it as a ‘motorsports’ tyre ;)

      1. aveli says:

        wishful thinking.

  7. Gaz Boy says:

    I would imagine that, apart from a brake/steering/axle failure (particularly the front axle), having a high speed blow out must be the most scary experience a racing driver can have – I’m thinking of Ralf having a chat with the wall at Indy 500 – and bear in mind he went in backwards, so at least the meat of the car took the impact. Imagine having a blow out that pitches the car nose first into a barrier or concrete wall? Thankfully, such incidences are rare – but as last year at Silverstone 2013 proved, the probability is always there.

    1. Gaz Boy says:

      Sorry, error, I meant Indy 2004, not 500!

      1. Random 79 says:

        It’s okay. You were only 1504 years out but still, the Indy 500: Back in the day it was the pinnacle of chariot racing :)

      2. Gaz Boy says:

        RE Random: knowing what the good old USA is like, then the chariots would have had off-set suspension, a live rear wooden axle and the horses would have have been chunkier than Montoya!

      3. Random 79 says:

        …and they would have been driving on the wrong side of the road ;)

      4. Gaz Boy says:

        Don’t forget pit stops for a bag of oats for the horses, a new set of horse-shoes and a can of Budweiser for Tod, Brad and Rod.
        Mind you, the year AD 500 was still in the recent post-Roman era, so it would have been Bradus, Toddus, and Rodus.

  8. Elie says:

    Very interesting article , I wasnt aware that teams couldnt even run rigs which could replicate the loads on a tyre during racing. If I were manufacturer team – I would be forming a partnership with a tyre company and give them all the specs to do the testing- i guess this is banned- but whose to know!

    This also higlights the need to do more testing. If the FIA (and in fact the teams) are focused on reducing R&D spending. They should allow more actual testing if it means we get more accurate results!.

    F1 is getting too stale with all these rules. I appreciate cost cutting but real workd testing might save money and improve safety in the long run..and heaven forbid we might even get better cars also!

    1. j says:

      What unlimited testing would give us is faster cars for the few teams with money to spend, splitting the grid into three or four distinct groups.

      Mercedes seems to have money to spend so they would be far in the front with better developed aero. RBR would be able to fix their power unit problems much more quickly and would join Mercedes in a two team race for the championship.

      If Ferrari was able to test constantly like they did in the past it could put them on par with McLaren but they would still be well back from the two leading teams but in with a chance. This would be the main (only) point of interest. Can Ferrari spend enough fast enough to catch the two new top teams.

      Williams, Sauber, FI and Toro Rosso, with their limited budgets and limited ability to test or iterate on new wings and bodywork, would fall back by seconds per lap in to the midfield as the season progresses.

      In the backmarker group I see Lotus falling back to join Caterham and Marussia. Whoever can find some money to run the car will have a chance to catch up by developing better setups while money problems at Lotus means they may not be able to test any more than they already do.

      Unlimited testing could be interesting for Ferrari fans but would be gutting anyone rooting for an underdog like Williams to do well.

      1. Elie says:

        Not unlimited testing just an extra test mid season for a few days

      2. Dave Emberton says:

        An extra couple of days on top of the 8 for 2014, or an extra couple of days on top of what was meant to be none for 2013?

      3. Andrew Carter says:

        They have four two day tests during the year now, 1 day of which each team will dedicate solely to tyre testing.

    2. kenneth chapman says:

      i agree

      1. kenneth chapman says:

        i agree with elie.

  9. Richard Piers says:

    No doubt the rigs are much more sophisticated nowadays but such rigs were around when I joined the industry more than 50 years ago. With only one manufacturer there is little incentive for innovation and not much for last years nonsense.

  10. Rich C says:

    The aerodynamics of F1 tires under load:

    Another fascinating example of “road-relevance” brought to you by those crazy boffins at the FIA.

    Or… not.

  11. F1.6T says:

    This is PURE GOLD, I tip my hat to Prof. Gillan, this is one of the most rounded tech articles produced for fans, ever!

    Nice1 James, just need an ex-driver willing to go into the finer points of operating and piloting a modern F1 and you got the full compliment of experts.

    1. Random 79 says:

      I’m sure James could lure Grosjean or Maldonado away from Lotus with nothing more than a bag of peanuts and a smile :)

      1. Gaz Boy says:

        Don’t forget a pint of real ale for them as well to wash down the peanuts, although Romain being French-Swiss he probably prefers a bottle of red wine!

  12. TobyS says:

    Makes me want to get my belt sander out and put a scooter wheel on it!

  13. Scott D says:

    Interesting article, but it just seems ridiculous with the current push towards road-relevant super efficient powertrains that F1 has stuck with archaic 13inch rims with high profile (and less efficient) tyres that disappeared from high performance road cars decades ago. Surely a switch to a minimum 18 inch rims is a must, as their behaviour should be more predictable and ultimately safer. I am sure that the teams are more than capable of designing appropriate suspension systems to compensate for the lower profile rubber.

    1. aveli says:

      f1 tyres need to be tall with 13inch rims because the tyre wall acts as a spring. a lower profile tyre would result in an uncomfortable ride and the tyre mass may not be big enough to distribute the heat generated in the tyre so they will melt a lot more than they currently do.

      1. Scott D says:

        I don’t believe that 13 inches is a technical limitation at all as Michelin were all for the introduction of 18 inch F1 rims only last year. A company like that would not make such a suggestion without foundation. As I have said, any issues relating to lack of suspension travel would be overcome by the teams and I dont really see costs as a barrier either, as everything costs in F1, only a lack of willingness to move forward.

      2. aveli says:

        you’re right the suspension could be uttered to accept an 18in rim but the rubber mass on the tyre will be much less which would lead to the tyres over heating. the current tyre mass just about cope with the heat.

      3. Scott D says:

        @aveli. I would be interested to see the source of your info. Otherwise we may have to agree to disagree on that one!

  14. SteveH says:

    Interesting article Mark, thanks. Are the tire beads attached in any way to the wheels or are they, like ordinary street tires, held on by a steel bead and tire pressure? With the cornering loads of an F1 car it would almost seems necessary to attach the bead in some way.

  15. JB says:

    https://www.youtube.com/watch?v=U-fEn1NHh4o

    Some slow videos of F1 car (with nice looking nose). Watch how the tyres slips at the start.
    Also, how water gets splashed up behind the wheels.

  16. Tyler says:

    Very interesting article James, as always these are my favorite stories to read on your site. Keep them coming.

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