Pirelli's poor consistancy a reflection of their road tires?

[DaveW]

How did they do that Dave? Besides being against the rules to doctor the tires, I believe they are sequestered prior to the race.

The theory doing the rounds is that if Pirellis are subjected to one hot lap & then rested overnight, they become more durable. Not sure about the chemistry, however.

JET: You should be right, but I suspect they need more time (distance) than they are allowed currently to be effective.

[strad]

I was under the impression that they had to turn in the tires..the only ones they get to keep in their possession, in parc ferme, are their qualifiers.

[DaveW]

Strad: extract from formula1.com, summarising 2011 tyre regulations:

"Tyre allocation has been reduced for 2011, with 11 rather than 14 sets of dry-weather tyres available to each driver per race weekend. Drivers will receive three sets (two prime, one option) to use in P1 and P2 and must return one set after each session. A further eight sets will then be at their disposal for the rest of the weekend, although one set of each specification must be handed back before qualifying."

[Sayshina]

The main point of this, is that I don't think I've EVER seen a single instance of something being clear cut, absolutely, globally better to go in one direction. E.g.: "Shorter sidewall is better for handling!"....

... Or, "pull rod is always the best solution, no reason to ever run a push rod!". Or, ...

That said, I haven't seen your specific questions. Feel free to repost them.

But sir, if you wander over to the pullrod thread you'll see me making the argument that if pullrod were so inherently superior nobody would have ever used pushrod to begin with.

I'd also point out that I made no claim to shorter sidewalls being at all superior. I made the claim that people who clearly have inside information have gone on the record as claiming that todays F1 tires look the way they do because of the rules, and only because of the rules.

I would actually be very surprised if that meant they were superior in all ways, as you are correct, that rarely happens. Much more often it's a case of one solution being slightly superior to the other once all compromises are summed up.

Jet engines can not really be claimed to be superior to turboprops. But while they are much less efficient they allow for much higher speeds and lower noise levels and those 2 factors alone meant it was inevitable they would take over both the airline and combat aircraft markets.

Remember, I'm a bike guy. I assume you have a passing knowledge of what's been going on with bike tires over the last couple of decades. Profiles are constantly being fiddled with as they have a vastly greater effect on vehicle performance than their 4 wheeled counterparts.

A "V" profile front might allow the bike a bigger contact patch on its side, but make it too sharp and the rider will feel like the bike is trying to low side him.

Ciro: I actually feel like we need to get off Pirelli's back a bit. Historically it's taken a full season or more for new tire manufacturers to get up to speed, and to my knowledge nobody has ever been asked to copy another company's product before. I'm very impressed with the job they've managed to date.

The people who do not use them made a list of demands to Pirelli, and the results were universally despised by the people who do use them. Pirelli has done an incredible job of balancing between the competing demands.

One could also take heart from looking at WSB, where Pirelli has been the control tire for a number of years but continued to develope and advance their product. I somewhat doubt the FIA will allow them to do that in F1, but at the least it shows they might be willing if given the chance.

It's been 1 race. They're going to have better and worse performances this year, but as long as they manage to not have an Indy I think we should all consider this a successful transition.

Oh, and JT, my question as far as it goes in this thread was:

Given that a number of persons directly involved with F1 have over the years claimed that F1 tires would have a different aspect ratio if allowed, could you give some insight as to why they might be either mistaken or deceptive?

[Jersey Tom]

Which people? Who specifically? From what background? In what context? There are plenty of people with high level vehicle backgrounds and think they know what is best from a tire standpoint. Some do here and there, some don't.

A few things to consider... and these are only the ones I consider common sense or that you can follow up with in the public domain:

1. Contained air volume. Rule of thumb is the higher the loads you have to withstand, the more you need for safety/durability. Big wheels and tiny sidewalls and your load carrying ability shrinks dramatically. Ever notice how the super skinny profile sportscar tires are typically LL rated, rather than SL or XL? Downforce and load transfer... F1 cars generate some substantial load.

2. Consider how many people are incredibly horny for unsprung mass and rotational inertia. I know open wheel race teams who would go to all Ti fasteners to save however many grams of unsprung, rotating inertia - despite being very expensive. Now consider replacing the ultra thin lightweight sidewall of a F1 tire with metal. Even the rim itself... you're bumping the shell's OD from ~13" to ~18"? MR^2... mass will go up proportional to R, and then there's the radius term itself. +165% from the circumferential bit of the rim itself.

3. Compliance with the road, with camber change, etc. Would you rather have a tire that can absorb these things, or is so damn rigid that if you get it outside of the orientation it wants, your grip goes to ---?

4. Last but most importantly - WHY CHANGE? It's outrageously expensive for everyone involved. Teams have to completely redesign their cars. Tire manufacturer has to totally redo everything. New brakes. New shocks. For what gain? Don't see F1 tires being blown out from overload. The cars are already outrageously fast and incredibly responsive... to the point where rules have been put in place to limit their speed frequently (grooved tires, smaller engines, aero restrictions...).

If F1 was on bigger wheels as a platform in general I could see this whole argument going in reverse. "Why are we on big wheels with high rotating inertia, when we can get away with using 15 or 13" bead diameter while still having enough brake to decel at up to 5G, and all the yaw response we need."

[Sayshina]

As to the "who", I'll just say Michelin as they're the most recent ones I can remember. They requested exactly this change. There have been many over the years, but I wasn't paying attention and certainly wasn't preparing for this exchange.

And remember, I'm STILL not making any claim that it would be clearly superior, I'm just noting that many people have said the tires would change.

F1 cars generate significant load only in respect to what they start out as. Vertical loads are still within the range of your average SUV or large PU.

I have no information on the construction of F1 tires, but in the formulae I've been involved with the tires are significantly heavier than the wheels volume for volume. When race bikes started trending toward 16.5" rims instead of 17"'s while maintaining the same rolling dia., the unsprung weight went up, not down.

How thin could the sidewall be? It's still got to contain the lateral load, and I would assume the taller the sidewall the more matereal you'd need to maintain integrity. After all, you're somewhat limited on how much air pressure you can add. I have my doubts that anyone's running semi truck type pressures.

Mostly, and this is just my laymans guess, I'd expect the short sidewall to do a slightly better job of controlling the rolling radius, which seems to be the primary concern for the aero boys.

I don't really see the argument of the teams having to change as being all that valid. Even the tiny teams have to do that just about every season these days anyway, it's been a long time since we saw a team start with last years cars. Does anybody even use last years shocks? Didn't Williams say something about "We're using the same front jack as last year, and everything else is new"?

"WHY CHANGE?"? I don't really know. It's not my field. I've raced on 18" and 17", but I couldn't tell you one was superior to the other based on size. I could tell you why I liked one over the other, but in the bike world at least we keep going back and forth every few years.

What I can say is that other people, Michelin being the most recent, have said they want to change. Personally I think rules should be as few and as clear as possible. I don't see why the FIA can't stay out of the way and the tires would then find their ideal size organically.

[DaveW]

A well considered & interesting post JT. I think your logic is impeccable. I do have a small problem, however. What rims did CART, & do IRL (Indy), LMP1 & LMP2 use? Those vehicles are, or were, around 50% heavier than an F1 vehicle (give or take a little) &, while I do concede that CART & IRL lacked/lacks both quantity & sophistication in the aero department, I find it difficult to believe that F1 (with the endless restrictions imposed on the series) makes more D/F than a full blown LMP1 vehicle.

One difference between an F1 vehicle &, say, an LMP1 vehicle, is that the tyres used in the latter series are capable of making the suspension work with reasonable efficiency, so mechanical set-up does affect performance. I have heard many times from F1 engineers that "mechanical set-up has no effect on lap time". By way of contrast, the difference between a "good" & "bad" suspension set-up can be as much as 15 seconds per lap for an LMP vehicle circulating Le Mans.

[Ciro Pabón]

15 seconds is a lot and a very good point to bring in. However, being always the road obsessed guy I am in this forum, I ask permission to add that the track is almost three times as large as an F1 track, and, more importantly, it's a public road, ergo, with no rubber and with very serious bumps, absent in a racing track with no truck loads. I've ride on a bicycle the whole circuit and you wouldn't believe the state of the asphalt. I guess it would be almost impossible to ride this track in an F1 car and guarantee the same level of safety we're used to.

Darn FIA, they killed the straights (no straights longer than 2 km, you know, by rules), but they were straight only in one axis, that is longitudinally. Horizontally and vertically those ex-straights, already "chicanized", were as bumpy as the skin of a plucked goose in the middle of a Canadian winter night.

[DaveW]

I agree, Ciro. It did happen during pre-qualifying a few years ago, but I'm sure that much of the 15 seconds was from the driver's head.

I suppose the point I was trying to make was that a less compliant tyre (LMP1 tyres have around twice the vertical rate of F1 tyres) might force teams to pay more attention to mechanical set-up. Either that or insist that tracks are machined to billiard table smoothness to make them "safe".

[Jersey Tom]

Sure.. could do that.. but again, ultimately what's the benefit to the sport?

And yes, Michelin had made some request to go to 18" bead dia wheels. My suspicion is that it was either:

(a) Make their own manufacturing easier. If they have lots of build equipment for 18" stuff, then they don't have to front all the money to buy a large volume of 13" (their current 13" production volume requirement is probably not huge).

(b) Would put them in a good position when it came time for contract extension, as they'd be the only company with experience doing 18" F1 tires... as opposed to Pirelli, Goodyear, and Bridgestone who all at least had some experience with the 13" variety.

Just some theories. I'd lean more toward (a) than (b). Moot point now.

[Ciro Pabón]

Yes, DaveW, understood and agreed.

However, you know that safety is meaningless. You build something safer and people will find a way to go to the edge again.

I cannot avoid to point out that the flatter the asphalt, the more power you can deliver. The flattest asphalt in the world is a drag track. Any bump and you lose a piston, because of the load variation on the engine. We're talking 7,000 HP here, in drag racing.

Brainerd, the drag track, is so flat that's unbelievable. I saw it in 2004, when it was almost new. They used taconite (a very hard, dense rock with lots and lots of iron) as a base for asphalt. They have a super-flat concrete surface for the first 700 meters and then the smoothest asphalt surface I've ever seen. It is so flat that the difference in level between any two sectors is thinner that a sheet of paper and it had to be checked with lasers.

The point I want to make is that I were allowed to build the track as I imagine it, then you wouldn't need a suspension at all and JTom and Sayaishin would have nothing to discuss about tyres (just a joke, just a joke).

On the other hand, Le Mans, legendary as it is, has a surface that makes tyre and suspension engineer realize that the tyre is nothing without the track. They are made for each other, so to talk about the relative benefits of a tyre in abstract is a bit naive.

To exaggerate a bit, you need a different tyre for Baja than the one you need at Brainerd. I'm always amazed by the lack of "ground to earth" approach some people have... If I were given leeway, I can make the defects of any tyre/suspension combination come into light, just with a CAD and a paver (and perhaps a few kerbs).

Tyres are the "first line of defense" of a suspension, so low tyres are not good at bumps. Kerbs would be a headache, literally. The shorter the sidewall, the more grip you have and the less the tyre lasts. I'd say that car low profile tyres last 3/4 of a regular tyre and you're risking the life of your rims if you go out of the road for any reason.

As JTom points out, when you change the tyre, you change the car. If I understand him well, he also is pointing out that we're engineers, not physicists. As they say, "you'll know them by their fruits" and I think engineering is all about fruit.

I'm, taking advantage of your comment, Dave, also pointing out that when you change the track you have to change the tyre (ergo...).

[Richard]

As I recall, the idea of switching to 18" was to allow use of road tyre manufacturing equipment. It would also allow road car owners to brag that they had exactly the same tyre on their car as used in F1.

Hopefully it wouldn't be exactly the same, or the rubber would have useless grip on a normal car, durability would be sub-1000km, and slicks would be useless in the rain.

Maybe they'd have the bragging rights of the same shape and badge, and quietly ignore the completely different compounds and construction. So no different to now?

[strad]

Let's face it...They keep the sidewall they have so the cars don't have to have real suspension. IF they had a short sidewall they would have to have more suspension travel....ain't gonna happen, They want no movement so their aero will work...can't have cars bouncin around on shocks and springs ya know.

[ESPImperium]

Let's face it...They keep the sidewall they have so the cars don't have to have real suspension. IF they had a short sidewall they would have to have more suspension travel....ain't gonna happen, They want no movement so their aero will work...can't have cars bouncin around on shocks and springs ya know.

Sidewall will be changing in 2013 from my info. The cars will be on 18' wheels all round. Will see the cars weight increase by 30KG for the wheels alone, and the cars will see their suspension completely change. The cars will see their braking zones change, witch will see their entry speeds being slower, but their exit speeds being higher. Top speeds will probably rise by 20km/h as well.

The technology that will be used as a baseline for the tires will be the Le Mans 1000km tires seemingly. Michelin are believed to be working on tires for this formula, also Pirelli also have started with this formula of tire as well.

Personally i think that racing tires should not be a reflection on road tires, some will see it another way i feel.

[Jersey Tom]

Will see the cars weight increase by 30KG for the wheels alone, and the cars will see their suspension completely change. The cars will see their braking zones change, witch will see their entry speeds being slower, but their exit speeds being higher. Top speeds will probably rise by 20km/h as well.

Is that so.