How can teams resolve tyre issues?

[marcush.]

Comes back to the old saying then:

"Downforce is like money - it helps a lot to have it"


Thanks Marcus

Do the car used a different tire in the damp/wet conditions? - not jokeing here.
As it seems, that the current F1 cars are better/have less tire heat related problems on Intermediates as well, why the setup is still for the slick tire.

May indicating that the tire construction is better "suited" to the car.

spot on 747.the wets did not have that ultra stiff carcass ...imay add we raced solely on Nurburgring nordschleife...so mainly sweeping corners and lots off line driving through traffic ..as the rules are quite open with aero there you could
help yourself in that area .
off course a lot of the clever guys pointed towards the drivers not pushing hard enough ...back then I thoought it was my failing if they did not feel comfortable enough to do so...with hindsight ,and this is something I did in later years I would have ordered them to go out and do business before asking me changing the car...

[747heavy]

Wow 747,

Remarkable post! I actually get alot of what you are saying.
Thank you once again =D>

Thanks for the flowers !

I´m glad you do.

I know that there is no easy answer/explanation, when it comes to the interaction between cars/tires and the track. It´s very complex, there are many variables involved, the relationships are not linear,and things are not 2or3 dimensional and static.
It´s multidimensional,dynamic and at times very nolinear, some variables can´t be measured others can´t be directly influenced.
Some interactions/relations are not/poorly understood others overlooked or underestimated,
which in return manifests itself in problems in other areas.

It´s easy to paint yourself into a corner. If you make a wrong assumption or choose the wrong compromise, you can end up in a difficult place, from there it is often a long way back.

But you can eat a elephant only one bite at a time, and you have to start somewhere.
I know that I (over)simplify the things, and I know that Tom and some others will get a good laugh out of it - fair enough, I understand and I don´t mind.
The simplifications will lead to inaccuracies - like in the simulations/simulators the teams use.

Nevertheless I hope, that some of what I try to explain, will help some interested readers to understand, some aspects of the sport a bit better. That´s the whole purpose.
This is not a dissertation and not a scientific paper - nor is it meant to be.
I´m not trying to tell the F1 teams what there problem is - nor could I.
If I make a big blunder, I hope the people with more knowledge will come forward and correct me. I will be glad, when they do.

[747heavy]

@ Marcus

Thanks for the reply.
I don´t know your drivers, so I won`t/can`t comment on their ability.
But let´s assume, that they do there best, and not just cruising around.

Is it really possible to drive a car harder which has little grip?
Does not the tires become the limiting factor, so if you push "harder"
you just slide more? (graining, wearing the tires, but don´t generate much more heat)
Just thinking aloud here, and wanted to hear your opinion (and anybody elses as well)
To illustrate my point (in extreme), imagine driving your road car on ice,
can you really achieve more load transfer (lateral accl.), by driving/trying harder?

it´s a chicken and egg problem

You need to have grip, to get the load transfer to work the tire -> get more heat
-> get more grip, and from there it compounds and get´s easy(ier).
Low grip/cold hard tire, you push put the car may just slides, you push harder it slides
more, but you don´t really get more load transfer. No load transfer no heading the tires.
the same for aero, to get more downforce to help working your tire, you need to drive quicker, but this is easier said then done, with limited grip.

Where does the circle start? How you get your foot in the door - so to speak?

Warming up the tires well is a skill, some drivers are better in it then others, but I´m
not sure, you can just say try to drive it harder. (But I know what you mean with it)
It needs a lot of understanding from the driver to know, what he can and what he can`t do
and why.

I think in these conditions it is maybe easier/?better? to try to warm the tire with braking and acceleration, then trying to force more load transfer lateral by waving left to right etc.

Now, I´m fully aware, that this is not feasable in a race situation, more thinking about out laps etc.

The other thing which makes it more difficult for the driver in these conditions is, that
a car with a stiff suspension and stiff tire (little roll), gives maybe to little feedback
to know where the limit is, because a stiff setup will load the tire quickly, so it makes it easy to "overshoot" the availible grip limit. Small imputs will lead to (relative) large changes in CPL - difficult to "balance" the car at the boundary of the traction cirlce in this condition. (IMHO)

Any thoughts?

[marcush.]

@ Marcus

Thanks for the reply.
I don´t know your drivers, so I won`t/can`t comment on their ability.
But let´s assume, that they do there best, and not just cruising around.

Is it really possible to drive a car harder which has little grip?
Does not the tires become the limiting factor, so if you push "harder"
you just slide more? (graining, wearing the tires, but don´t generate much more heat)
Just thinking aloud here, and wanted to hear your opinion (and anybody elses as well)
To illustrate my point (in extreme), imagine driving your road car on ice,
can you really achieve more load transfer (lateral accl.), by driving/trying harder?

it´s a chicken and egg problem

You need to have grip, to get the load transfer to work the tire -> get more heat
-> get more grip, and from there it compounds and get´s easy(ier).
Low grip/cold hard tire, you push put the car may just slides, you push harder it slides
more, but you don´t really get more load transfer. No load transfer no heading the tires.
the same for aero, to get more downforce to help working your tire, you need to drive quicker, but this is easier said then done, with limited grip.

Where does the circle start? How you get your foot in the door - so to speak?

Warming up the tires well is a skill, some drivers are better in it then others, but I´m
not sure, you can just say try to drive it harder. (But I know what you mean with it)
It needs a lot of understanding from the driver to know, what he can and what he can`t do
and why.

I think in these conditions it is maybe easier/?better? to try to warm the tire with braking and acceleration, then trying to force more load transfer lateral by waving left to right etc.

Now, I´m fully aware, that this is not feasable in a race situation, more thinking about out laps etc.

The other thing which makes it more difficult for the driver in these conditions is, that
a car with a stiff suspension and stiff tire (little roll), gives maybe to little feedback
to know where the limit is, because a stiff setup will load the tire quickly, so it makes it easy to "overshoot" the availible grip limit. Small imputs will lead to (relative) large changes in CPL - difficult to "balance" the car at the boundary of the traction cirlce in this condition. (IMHO)

Any thoughts?

yes I do have my thoughts :I experienced some drivers who talked at lengths about the rear of the car being unsettled or wandering when cornering and they communicated this as nervous ness and oversteer.Reality was they felt nothing else than the tyres going into slip angle ..but instead of leaning on the car they interpreted this as an unstable condition.If you shy away from this feeling ,god its never going to happen ..as you need to dial in a lot more understeer into the car to prevent the thing from showing this wandering at the rear.
You can do a LOT with dampers there .. making the car more predictable in reaching slip angles...so timing the car reactions to create a linearity or progression in reaching slip angles is a key to build up driver confidence.. which will reap big big gains in lap time for those drivers who need this stability ...or call it trust in what the car will do will not hurt them ..
I´ll come back to this later..

[DaveW]

Incidentally this is one are where you still need practical experience of your tyres for a rig test to be relevant.

A good example was some rig testing that DaveW did for some customers a while ago. Two customers each with the same chassis, engine and tyre combination. the first car had a relatively poor PI as defined by Dave's test and this was improved significantly leading to less graining of the compound and more grip.

The second car had a lower PI to start with and had it reduced further. They simply couldn't get any heat into the compound and never performed that well.

This isn't to devalue the rig test - tyre stiffness values suggested by it have made me look good on more than one occasion but you have to have a context of track and tyre experience to interpret the results.

Ben

Mmm... The c.g. positions of the two vehicles differed &, as a result, the first worked its front tyres harder. Overall, the second vehicle probably required some re-ballasting or softer front tyres. Probably should have looked at more aggressive dampers. Having said that, I can't disagree with your conclusion. Interpretation is required to make the best use of rig tests. I note that we did explore different tyre pressure splits for the second vehicle, so I must have had concerns about the tyres.

[autogyro]

How about adjustable suspension useable only in out laps and practice.
To allow the driver to upset the suspension setings to fully work the tyres, get them to correct temperature for faster and more effective evaluation when the suspension is reset to optimum?

[mep]

@ Marcus
Did your Center or downforce pressure position change after you add downforce to the car?

[Jersey Tom]

I just think it's funny that everyone is assuming:
1) Majority of the problems are temp related
2) The problem is they don't have enough heat in the tread / tires need to get "worked" more

[747heavy]

I just think it's funny that everyone is assuming:
1) Majority of the problems are temp related
2) The problem is they don't have enough heat in the tread / tires need to get "worked" more

Good point Tom !

Not sure that the assumption is solely relatet to not enough heat in the thread.
I think that the problem relates more to not enough heat in the constuction of
the tire, limiting elasticity and thereby optimium deformation of the tire, to achieve
the desired contact patch pressure distribution.

But this could be wrong, as you correctly pointed out, what do we know from the distance - nothing and that´s right.

[DaveW]

I just think it's funny that everyone is assuming:
1) Majority of the problems are temp related
2) The problem is they don't have enough heat in the tread / tires need to get "worked" more

JT, I have no doubt that a tyre designer must consider many variables when he sets out to design a tyre for a particular application, and what those variables are & precisely how he manages them will enable him to satisfy that application (perhaps more consistently for some manufacturers than others) and, perhaps because the design & manufacturing process is largely heuristic, it remains a closely guarded secret.

Personally, I (like to think that I) don't have many stakes in the ground, but one of the most securely planted is the view that, once bolted onto a vehicle, a set of race tyres can be used or abused by the race engineer &/or the driver, & the accessible signatures of their "in service" health are temperature distributions & pressures. Apologies, but if you wish to demonstrate that my stake is misplaced, you will have to do rather better than passing unhelpful comments such as the one above.

[Jersey Tom]

Tread compounds...

Some gain grip as they get hot.
Some lose grip as they get hot.
Some are generally insensitive to temperature (there are pro race series where temps as a performance scalar are an afterthought, and camber / pressure / steering management is MUCH more important).

Sometimes when grip goes up, laptimes get faster.
Sometimes when grip goes up, laptimes get slower (yes, even with professional drivers extracting as much as possible from the tire).

Some use temperature spreads (pyrometer or IR) to tune their camber and pressure. Some think it doesn't have much value (I lean toward the latter).

Sometimes as the sun comes up and track temps go up.. tire temps go up. Sometimes when the track temp goes up, tire temps go down.

Sometimes if your steering settings are off you will have an impossible time managing tire performance and it will look like something bizarre with temperature and "working" or graining the tires.

Some pro drivers are really keyed into what the car and tires are doing. Some are clueless. Fewer yet can really communicate what they're feeling. Some just don't give a ---. Some are impossible.. they say they need or want 'X', and then when you give them 'X' they bitch. However, all of them think they are godly and know what's up and what's needed.

Point being.. does temp impact performance? Sure. But it can go any direction. Up, down, faster, slower, indifferent, whatever. Many teams have no idea what they're doing setupwise, in the respect of it it's significantly different from their competitors. So from where I sit.. for a driver or someone to say "Oh yea, heat is our issue, we can't work the tires enough (relative to other teams)" in a cool and confident manner is ridiculous.

If more heat was really needed across the board, it would be easy enough for Bridgestone to do. Could throw a compound on and have the tires at 300+ degrees. Doesn't necessarily mean it's the best thing to do

[747heavy]

Good stuff, 747.

I am particularly interested in your views on the compromises between "chemical" (temperature related) & "mechanical" (contact patch load related) grip. Also on lateral balance issues: moving the c.g. & c.p. forward will "work" the front tyres more but will "cost" traction & will increase initial understeer. What to do if the rears "go off" before the fronts start to "work" (appeared to be JB's problem in the second half of last season).

Also why do heated tyres still require to be "worked" on-track? (I think I know the answer to that, but your thoughts would be appreciated.)

Hello DaveW

I´m pretty sure you know the answer.

Why does tires still need to be "worked" on the track?
Well to put simple, to heat something about ambient temperature requiers energy.
If the energy input would stop or be reducted the temperature would drop, until you have
equilibrium again. That´s why pre-heated tires cool down on the track if you can´t maintain
enough "energy input". Tieres cool down in safety car laps etc. - this leads to a drop in pressure, changing the stiffness of the tire, with the tire in this condition, you are may not able to put the "heat/energy" back into the tire.

As for the other question.
I can see that moving the CoG forward is a two sided sword. It will put initialy more vertical force on your tire (more grip), but on the same tokken, your tire will need to support the extra weigth in lateral direction as well - needing more gip.

I´m not sure why a forward CoP would increase understeer, assuming all other things equal.
But may I miss something here.

[747heavy]

@ JT

Agree with your observations in general.

But is it fair to assume, that for a given tire (compound/construction etc.)it is
possible to say, if the lack of (momentary)grip is due to insufficient heat or due to too much heat,in a given situation.

[747heavy]

@ DaveW

I don`t know enough about F1 setups in particular, so I admit that I´m not in the position
to make a comment here.
But as a thought.
On problem, I could see, is that they can`t work the tire more by making the front stiffer,
as they are probably allready past a point where the spring deflects much anyway, unless its
under braking or high aeroload or/and a combination of the two.
If you want to call it that, they ae may at the saturation point in terms of suspension stiffness. Any increase will not lead to more defection of the tire. The tire has become the
"main spring" allready.

I may have a suspicion, that a vertical upwards movement of the front tires, due to track irregularities etc, get´s transfered to the rear - working the rear tires more.
So any increase in front stiffness in this situation, may does not help the front, but make the rear tires "worse" in the longrun.

So there is maybe some work on the rear of the car requiered in order to fix the front problem, in respect to damper/inerter and sprin settings.

But as I say, I don´t know enough about the specifics of a F1 car.
And all what is said here is based around the assumption that the front tire is too stiff in relation to the rear tire (in terms of vertical stiffness).

[JohnsonsEvilTwin]

How do you measure what is going on between the road and tyre, or contact patch?
By the amount of force it takes before losing its critical grip I would assume?

If this is the case, perhaps the chemical reactions happening on this contact patch are the key to understanding this fully.
As the contact patch will be hotter than the rest of the tyre(in movement, relative to the rest of the carcass) I would assume the rubber to less solid than at any point in its revolution.

Of course you would also have a mean general temp for the whole tyre.

By knowing what happens at this point, I reckon you would be more than 50% the way to "resolving tyre issues". Of course I could be very wrong, but my opinion is slighlty better informed now thanks to some very good posts and posters on this thread.