40 replies to this topic

[wegmann]

So far this season I've heard that McLaren and Ferrari have trouble warming up their tyres enough for the one-lap qualifying sessions. I don't remember any rule about how warm the tyre warmers are allowed to be, so why can't they simply make them even hotter?

I've been told in the past that they only heat up to around 80 degrees Celsius, which is quite a bit less than the tire's optimum temperature, and I still don't know why that is either.

edited: thanks Engineguy, Celsius not Fahrenheit!

[Engineguy]

Are you sure that's not 80° C (176° F)? The ambient air temperature is more than 80° F for at least half the races, which would make tire warmers worthless.

[fasttrack]

Wow, that's my first post here on the Tech Forum. I am not an engineer, so let's see what I can contribute here...

I wondered about it too since a long time ago. It seems to me that there are a few extra factors into play here, the main one being the way heat is transfered through the tire structure. Tires are subject while racing to a fine balance: heating via friction, and cooling via air flow. It is quite possible that the tire is hotter a few mm inside the structure than they are at the surface (no, I dont have any data, it's just a sensible guess). Following this reasoning, warmers would have to heat the tire surface a lot more to be able to make the inner structure reach the optimal temperature; at this point, it is quite probable that the tire surface would start to degrade due to excess heat and no cooling.

It's all a theory. I'm sure there are better people around here than myself to answer it.

[jpf]

Yeah, that rings a bell actually. I think I remember hearing that the basic reason is that the temperature distribution within the various parts of the carcass/tread in a working tire on the track can't really be replicated by the tire warmers.

Which makes me think that the situation must be that in order to get the carcass and sidewall to temperature in a blanket, the tread would have to be made too hot, which I guess might lead to bad break in, graining, or excessive wear in the initial laps (just guessing). They probably warm the tire as much as the tread can stand, and then the opening laps (and all the tossing of the cars around) are to get the carcass up to temp.

Does anyone who actually knows what they're talking about have anything to add?

[Engineguy]

Just saw an advertisment in Performance Racing Industry for tire warmers. Says, "Enjoy a 180 degree tire from the green flag."

Went to their web site... their Pro-Line model ($1950 /set of 4) quotes:

Adjustable from 100-212 F, in 1 degree increments with the push of a button.

They have some info about tire warming practices on their FAQ page.

www.chickenhawkracing.com

[ciaoduc1]

1 degree!! Do you recon that's necessary or just a function of the rheostat?
Do you suppose the tire warmers are just as much for getting the air inside the tire warm as actually heating the carcass?
Any idea what tire pressures the teams run? And how exact are they?

[Antoine]

AT the begining of the first lap you have a lot of thing that cool the tire. Brake are not at the right temp. like the rim so you can't brake hard so you don't warm the tire a lot...
The tire are not hot so you can't go fast in the corner and you don't warm a lot the tire...
I think it still rigth in F1 the first thing that cool the tires is the track itself! before warming it under strain.
A tire warmer is better than nothing, but it not warm all the part!
On the 24h of Le Mans, they use some heaven to warm tire and rim! the brake still hot! so they can go fast quickely.

[Rat_Fink]

Originally posted by ciaoduc1
.........Any idea what tire pressures the teams run? And how exact are they?

From what I remember typically about 18.5psi. This only then tends to vary +/- 2psi within different set-ups.

This is based on knowledge from a couple of years ago so may have changed slightly in response to the new constructions introduced with the new tyre regs.

I remember a study being done into the effect of tyre pressures on the overall wheel rate and the engineer's staggering finding that IIRC a 1psi difference was equal to 10 increments in torsion bar stiffness!

Scary!

Makes you think that using a car on a 7-poster rig either requires rigourous checking of the tyres used and their pressures or even better, a move towards mechanical tyres that more accurately model the vertical stiffness and damping of a rotating tyre.

[perfectelise]

should be good to warm the wheel which would then radiate heat to the tyre's inner surfaces

[wegmann]

If the basic reason here is true ... that they're warming the "wrong parts" (the tread rather than the inner carcass), why not try to warm the right parts? How about a tire pump that continuously cycles between deflating the tire a little and then pumping back in hot air? And surely there must be a way to warm up the brakes a bit ...

In other words, if McLaren and Ferrari are truly having these problems, and they can gain a half-second by having tires the right temperature, is there really no legal solution?

[wegmann]

Originally posted by Engineguy
Just saw an advertisment in Performance Racing Industry for tire warmers. Says, "Enjoy a 180 degree tire from the green flag."

Went to their web site... their Pro-Line model ($1950 /set of 4) quotes:

Adjustable from 100-212 F, in 1 degree increments with the push of a button.

They have some info about tire warming practices on their FAQ page.

www.chickenhawkracing.com

This appears to do a nice slow warm which can heat up everything over 40 minutes. I guess it does take a while, though ...

[Greg Locock]

Neat idea - take it one step further, fit two tire valves and circulate the hot air continuously.

[Wuzak]

Didn't someone invent a microwave heater that could take an F1 tyre wheel assembly and heat it through? I believe it was banned....

[ciaoduc1]

What is a 7-poster rig?

[Greg Locock]

A 7 poster is a 4 poster (ie a hydraulic ram for each wheel) with three more to control the sprung body.

How would you go microwaving a STEEL radial? on an alloy rim?

I'm not saying it can't be done, but it isn't a bowl of frozen peas either.

[Oho]

Originally posted by fasttrack
Wow, that's my first post here on the Tech Forum. I am not an engineer, so let's see what I can contribute here...

I wondered about it too since a long time ago. It seems to me that there are a few extra factors into play here, the main one being the way heat is transfered through the tire structure. Tires are subject while racing to a fine balance: heating via friction, and cooling via air flow.

Actually I would think internal deformations are a significant source of heat as well, that is tyre carcass isn't simply heated by the heat conducted from the surface but internal friction related to deformations also significantly contribute and that would be difficut to emulate.

[Antoine]

How about a tire pump that continuously cycles between deflating the tire a little and then pumping back in hot air?

Yes, but what pressure you put in the tire?
When you warm tire, you do the pressure before on a cold tire!


I heard about the microwave I think it was in racecar engineering mag!

[Wuzak]

Originally posted by Greg Locock
How would you go microwaving a STEEL radial? on an alloy rim?

I'm not saying it can't be done, but it isn't a bowl of frozen peas either.

From memory the inventors had some way of getting around the wheel problem. And I believe that it was designed specifically for F1. Do F1 tyres have steel in them?

[McGuire]

Tire warmers are thermostatically controlled to around 175 F which is the effective temperature threshhold of the tire. If the tire/wheel assembly is left in there long enough (45 minutes is the typical spec) all will be nicely baked to a uniform temperature: tire, wheel, and air inside. I guess I don't understand the problem or the course of discussion. Is there something about the qualifying procedure that prevents suffcient time in the warmers?

[schumyfan]

Originally posted by McGuire
Tire warmers are thermostatically controlled to around 175 F which is the effective temperature threshhold of the tire. If the tire/wheel assembly is left in there long enough (45 minutes is the typical spec) all will be nicely baked to a uniform temperature: tire, wheel, and air inside. I guess I don't understand the problem or the course of discussion. Is there something about the qualifying procedure that prevents suffcient time in the warmers?

The problem is that teams like Ferrari, McLaren and Sauber last year have complained that the tyres are too cold in qual and they don't have single lap performance. So there must be some issues getting the tyre heated. The assumption of this discussion is that, the tyre warmers can't heat tyres upto their optimal operating temp and hence the discussion is about how/why/why-not of the tyre warmers.

I was thinking of something... If the problem is that, to get the core of the carcass upto the right temp, the treads need to be over-cooked, then why not try some other heating methods. Circultaing hot air was one suggested above. But how about having electrical resistance elements INSIDE the tyre carcass? Then they could just plug the trye to an electric supply and heat it from within. Is there a prblem with this or are there any regulations which ban this?

[ciaoduc1]

I think weight, balance, complexity, limited usefulness (only before the first lap).

If for some reason these problems aren't problems then they could wire the tires into the cars electrical system and have a constantly monitored/regulated tire heat system...while they're at it they could install a tire inflation system too. They could control it through variable track conditions. Strait -- jack the pressure up for less rolling resistance, Turn -- lower it for more traction, etc...hmmm...

[marion5drsn]

Why do we even need tire warmers? Aren't racing costs getting out of sight and many racing groups won't allow them and still put on a good show. Just another way to put F1 racing in a box as if tire warmers are really a big thing in racing. They should be outlawed! Do you put tire warmers on your car?
M. L. Anderson

[Greg Locock]

I think you are right, the decision should be made on cost grounds. However, I have a sneaking suspicion that because they reduce the difference between cold and warm performance they give a bigger benefit to the the teams that do the least testing, ie the poor ones.

Or am I just being contrary?

[McGuire]

Tire warmers are now down to around $2000 per set, so cost is not so much an issue as it once was. Take them away and the biggest edge will go to the drivers who have the car control to hustle the car on cold tires.

Driving on cold tires is very difficult not only due to lack of tread grip, but the very low pressures...the ride height is low so the car is dragging everywhere, and wobbling around on its sidewalls as well. Pretty treacherous really. This was one dept. where Montoya excelled when he was in Champ Cars. I agree with Marion: dealing with cold tires should be part of the driver's skill set.

[Engineguy]

From a pragmatic standpoint, if your average driver is going to, say, once a season, because of the diabolical nature of cold tires, destroy a $35,000 nose/wing assembly and a $30,000 suspension corner on a street course, or a $120,000 smashup of the right side of the car on an oval, suddenly eight or ten thousand dollars worth of tire warmers seems like a pretty smart deal. I don't get the whole point that a driver should be able to handle cold tires. A driver should be able to "handle" oil on his tires too, I guess... but I'm not in favor of a rule requiring the teams to smear grease on the tires at each pitstop.

[random]

I'd like to see the back of tyre warmers, but I don't know if F1 can manage it politically. This because low tyre pressure was implicated as a possible cause of Senna's Imola shunt in '94.

Max Mosley's primary "stated" agenda is safety. Getting rid of warmers could easily be argued as a big step back into the bad old, unsafe days.

[Wuzak]

Of course that argument only holds for starting the race or after a tyre change in the pits. Just look at what happened to Schumacher's tyres during one of teh safety cars at Spa last year. His tyres were wobbling all over the place.

Staring with cold tyres the pressures can be set accordingly, so low pressure wouldn't be a problem, And don't the tyre valves in F1 release air to maintain the set pressure? Of course once the air is gone it can't be replaced on track.

[Fat Boy]

Good drivers always excel on cold tires. The grip is low and feedback is vague, but because they have a hell of a grasp of both, they can still get the job done.

In a race and in qualifying, I'd rather see a driver have to deal with the cold tires.

When testing, running tire warmers can be a money _saving_ proposition. Consider this. The driver goes out and takes 3 laps around the track getting the tires hot and then runs 3 laps to get a good read on the car. You just have spent 6 laps to get a read on a chassis change. Around a smallish test track (say 1 1/2 miles) this is not excessive. OK, option 2. You have tire warmers on. The driver rolls out of the pits and runs his 3 laps to get a read on the chassis change you just did and then comes in.

So by using the tire warmers, you've wasted less fuel, fewer chassis miles, fewer tire miles, and most importantly less time to get the same read. The $2000 that McG mentioned for the tire blankets gets recouped very quickly.

As far as the temps that the tires are kept at, the F-1 teams have that sussed out. If they can design, build, test, and race a car, then they are certainly bright enough to know where to put the knob on set of tire blankets. Jeez, give them a little credit.

[McGuire]

Originally posted by Engineguy
I don't get the whole point that a driver should be able to handle cold tires. A driver should be able to "handle" oil on his tires too, I guess... but I'm not in favor of a rule requiring the teams to smear grease on the tires at each pitstop.

My take is it's auto racing, it's supposed to be hard.

That said, you don't see too many champ cars get banged up on cold tires; normally some guys are just faster than others and that is something I enjoy looking for and watching. I say let the wankers pay their way while the pros earn their pay. The parts killer on champ cars is the curbing, which guys seem to be able to find on cold or warm tires. On the Lola a good curb strike will bust the pedal box out of the tub. Big bux to fix.

[Ross Stonefeld]

Having the pedal box unseat itself mid-corner surely goes on the 'must-not-try' list of racing adventures

[McGuire]

Originally posted by Fat Boy
When testing, running tire warmers can be a money _saving_ proposition. Consider this. The driver goes out and takes 3 laps around the track getting the tires hot and then runs 3 laps to get a good read on the car. You just have spent 6 laps to get a read on a chassis change. Around a smallish test track (say 1 1/2 miles) this is not excessive. OK, option 2. You have tire warmers on. The driver rolls out of the pits and runs his 3 laps to get a read on the chassis change you just did and then comes in.

Quite so; the IRL allows tire warmers and I watched them at work at the recent test at Sears Point. It was a very cool day and the warmers saved a lap on every pit out.

[wegmann]

Originally posted by Fat Boy
As far as the temps that the tires are kept at, the F-1 teams have that sussed out. If they can design, build, test, and race a car, then they are certainly bright enough to know where to put the knob on set of tire blankets. Jeez, give them a little credit.

I have no doubt that they can set a knob appropriately, and yet I still hear that some teams can't get their tyres warmed up for one lap qualifying. So what's the holdup? That's essentially my question. Or is somebody just making up excuses for their consistently poor qualifying performances?

[Lukin]

I think the issue with the qualifying would more be the tyre's response to the heat, not the heat itself.

[alfa1]

Originally posted by wegmann


I have no doubt that they can set a knob appropriately, and yet I still hear that some teams can't get their tyres warmed up for one lap qualifying. So what's the holdup? That's essentially my question. Or is somebody just making up excuses for their consistently poor qualifying performances?

During normal on track running, the wheel assembly is much hotter (brake heating) than the surface of the tyres? Does that mean the optimal tyre temperature, the way the manufacturers desire it to be, is one with a temperature gradient from outer surface to inner for optimal functioning?
Since this isnt simulated with the tyre warmers, maybe thats the problem.

[wegmann]

Originally posted by alfa1
During normal on track running, the wheel assembly is much hotter (brake heating) than the surface of the tyres? Does that mean the optimal tyre temperature, the way the manufacturers desire it to be, is one with a temperature gradient from outer surface to inner for optimal functioning?
Since this isnt simulated with the tyre warmers, maybe thats the problem.

I believe we've been over this higher in the thread. So why not heat the wheel assembly, too? Maybe there's a rule, but I'm not aware of it.

[JwS]

The issue I believe is this:
The wheel tire assembly can be raised to the appropriate temperature by the tire warmers, but between that point and the start of the qualifying lap too much temp is lost. The operating temp can only be maintained while running near full speed on the track, all other times you are cooling off. This is based on my experience using warmers on my motorcycle, and of course any issues I had in this are probably 200 times worse on an F1 car!
JWS

[fasttrack]

The problem is complex, because we're not talking about something static. There are numerous sources of heat (friction, tire deformation, heat from the brakes) and sinks (airflow, heat conduction over the wheel mount) as to make it very dependent of the entire design of the car... and its interaction with a given track & weather.

For example, airflow. There may be subtle differences in airflow around the front & rear wheels, and it may make the tires cool down faster for some cars than the others.

The heat conductivity of the tires themselves may be at play too. A tire that conducts heat better will keep a more uniform temp, but will also cool down faster when on a straight.

Another good point was the possibility that some tires (Bridgestone?) may behave better with a more balanced heat distribution... while others (like Michelin?) are less sensitive to the distribution. This would change the behavior of the tire a lot (of course, it can be the other way around!)

The heat from the brakes is also important, and again, details of the design may transfer part of this heat into the wheel rim (which would be used as part of the refrigeration system, in a sense); or the heat may be 'isolated' from the wheel rim and dissipated elsewhere.

All these factors surely come into play and make this something very difficult to analyze. It's no wonder cars behave differently.

[wegmann]

Well if Ferrari isn't doing exactly what somebody suggested here ... heating up their wheels with a special device! Front page on the Autosport/AtlasF1 news today ...

[J. Edlund]

Originally posted by wegmann
Well if Ferrari isn't doing exactly what somebody suggested here ... heating up their wheels with a special device! Front page on the Autosport/AtlasF1 news today ...

There are "tire ovens" working on the same principle as a microwave oven and they are said to heat the tires better; wouldn't be allowed in F1 though.

[Christiaan]

Funny that, as I was scrolling down this threaD I was thinkintg ovens too. When this BB wqas born we used to imagine that engineers surfed Atlas all the time to see what brilliant ideas we were discussing. So did the Ferrari problem go away?

[charlie64uk]

On touring cars i heated the fronts to 70°C and the rears to 50°C (rear wheel drive).This helps to put temperature in to the top surface of the tyre and was carried out for 1 hour.The difference in temperature due to the characteristic of the tyre as the rears come in a lot sooner than the fronts.Due to the carbon brakes run on the car it was possible to blank off some of the brake cooling and put extra heat into the brakes which then heats up the wheel and tyre also a lot quicker,this being good for qualifying.
Nitrogen also used to reduce the pressure fluctuation.