Radial vs Cross-ply Tyres

[williamssam]

David Coulthard recently mentioned in an interview at Autosport International that F1 tyres are radials and as a result the drivers can't slide the cars as much because they operate at lower slip angles. I was under the impression that radials are outdated and the benefits of cross-plys far outweigh any benefits there might be to using radials. Could anyone shed any light on this?

[MrT]

Radials have more compliant side walls and a stiff tred section, and contact patches are maintained, in general, more consistently... I run cross ply slicks on our hillclimb single seater, and have heard that the radial versions to produce better peak grip but are quite edgy, they don;t slide as much and give up very quickly. Peaky slip curve as the graph below shows..




As I run in hillclimbs, where one mistake means you loose its important to have a drivable car, and therefore the crossplys I think are our best option.

[Roland Ehnström]

F1 ran bias ply tires until the early 80's, and they could slide those things around in a way that's totally impossible with radials. I hope bias ply will one day make a return to formula one, but it is not likely...

[Jersey Tom]

If by "you cant slide the car as much" they mean you cant be a sloppy driver, then yes.

Other than that I can't imagine any reason to go back to bias ply tires. There's no way it will return to high level motorsport.

Edit - This is a good read.

https://rsracing.com/tech-tire.htm

[ginsu]

If by "you cant slide the car as much" they mean you cant be a sloppy driver, then yes.

Other than that I can't imagine any reason to go back to bias ply tires. There's no way it will return to high level motorsport.

Well, I don't know why Hoosier would make such a large selection of Race Rubber that's bias ply if they didn't perform well. I know we have them on our Formula SAE car, but that might be due to cost more than peak grip.

Most racing radial tires are closer to a belted bias ply tire than a passenger car radial tire. This gives the racing radial tire traits from both bias & radial tires (good feedback & higher breakaway traction). Which tire is best for you, it depends on your needs. The bias tire is good for applications where negative camber is limited, but only if a wide enough rim is available. Radials are good where transient handling is primary concern, and adequate negative camber is available.

Bias Ply vs. Radial performance

Bias ply tires differ from radials on the following items.

* Static negative camber requirements are less, usually about 1 to 1 1/2 degree negative is sufficient.
* Rim width selection is more critical, because the tread face is flexible, the rim helps support the tire. The rim width should be as large or larger than the section width of the tire.
* Air pressure can not be used to reduce sidewall flex (rollover). Excessive air pressure will cause the tread face to bulge, reducing the contact patch.
* Bias ply tires give more warning (than radials) about traction limits and have excellent feedback of what the contact patch is doing.
* Bias ply tires operate at larger slip angles than radials. This larger slip angle is what makes bias tires feel sloppy on initial corner turn in. What this means to the driver, you have to 'lead' the corner more to account for the slip angles.
* Because of how bias tires react to cornering loads, the tread can be thicker than radial tires.

Radials differ from bias ply on the following items.

* Radials generally need more static negative camber than bias tires.
* Radials generally provide more breakaway grip than a bias tire.
* Radials give less warning before 'breaking away'. This causes radials to be harder to drive at the limit.
* Air pressure can be used to reduce sidewall rollover, without having the tread bulge like a bias tire. The may allow you to use a larger sized tire.
* Radials are usually heavier than bias tires due to the over wrap plys.
* Radials operate at lower slip angles than bias ply tires. The is the main reason Radials have better transient response than bias tires.

[Jersey Tom]

Racing radials, are still radials. Not bias ply (even if they incorporate some features from them).

Hoosier, Goodyear, Avon, et al still make plenty of bias tires, yes. For low-level events like Formula SAE where driver skill isn't that terribly impressive for the most part it makes more sense to have a tire thats forgiving and easier to drive on.. not as peaky.

Look at any top-end motorsport.. Formula 1, ChampCar, GP2, hell even NASCAR. All on radials. There's a reason for that.

And FYI even in FSAE, Michelin and now Hoosier have been quietly developing radials for the competition.

Going back to bias tires in F1 would be like saying "Well lets go back to not having aero. Sure we wont have as much peak grip but the car will be a little basic and easier to drive"

[Roland Ehnström]

I kinda disagree that going back to bias ply would make it "easier" to drive an F1 car. The aim will always be to drive as fast as possible, and to be fastest of all will always be extremely difficult. If you think the car is easy to drive, you're simply not trying hard enough. Going back to bias ply tires will not make the driver's life easier, it will force the drivers to drive differently, that is, it will force the drivers to slide the car around more in order to go really fast. Those powerslides and four-wheel-drifts would help the audience appreciate just how difficult it actually is to drive an F1 car on the limit. With radials, in my opinion the cars look too much like they are "on rails", and the only time you see any real input from the driver is when he makes a driving error. With bias ply tires, the driver's skill would shine through much more, and not only when he makes a mistake. I think that would be very good for the sport.

I know, this is F1 Technical, so the members here will generally be more interested in the technical bit than in the drivers. I guess I differ from the majority here in this respect. In my opinion, F1's greatest asset is the drivers, and I think it's such a waste when their awesome skill is masked by technical inventions. In this respect, F1 was better in the 60's and 70's, before anyone had heard of such things as semi automatic gearboxes, traction control, active differentials - and racing radials.

Here's an awesome clip of Patrick Depailler driving a Tyrrell on a very wet Montreal track in 1978, on what to me looks like (bias ply) SLICKS, even though the commentator (Murray Walker) sais they are rain tires. I don't know why he would go out on slicks in these conditions - maybe he just wanted to show off for the camera?! But anyway, this clip shows the kind of driving skill that I wish we could see more of in modern formula one: http://www.youtube.com/watch?v=KqZBJCFS_Ng Crank up the volume!

[ginsu]

Look at any top-end motorsport.. Formula 1, ChampCar, GP2, hell even NASCAR. All on radials. There's a reason for that.

And FYI even in FSAE, Michelin and now Hoosier have been quietly developing radials for the competition.

Going back to bias tires in F1 would be like saying "Well lets go back to not having aero. Sure we wont have as much peak grip but the car will be a little basic and easier to drive"

Yea, I won't argue that radials are here to stay and offer better grip when setup properly. But some people do like a forgiving tire that isn't camber limited, and that's why bias ply are nice for autocross tracks. Personally, it works out good for me because I don't like to run a lot of negative camber on my daily driver so I can put on a set of bias-ply R-compound hoosiers (not DOT legal of course) and run my 'street' suspension setup on the track with little compromise.

Here's an awesome clip of Patrick Depailler driving a Tyrrell on a very wet Montreal track in 1978, on what to me looks like (bias ply) SLICKS, even though the commentator (Murray Walker) sais they are rain tires. I don't know why he would go out on slicks in these conditions - maybe he just wanted to show off for the camera?! But anyway, this clip shows the kind of driving skill that I wish we could see more of in modern formula one: http://www.youtube.com/watch?v=KqZBJCFS_Ng Crank up the volume!

To be honest, while that is a good clip, it looks like he was going pretty
slow to me, at least compared to today's speeds. Also, he may have had full ground effects with side skirts, too.

Canada
Fastest Lap 1978: Alan Jones 1'38.072

Canada
Fastest Lap 2005: Kimi Räikkönen 1'14.384

[zoic]

I Here's an awesome clip of Patrick Depailler driving a Tyrrell on a very wet Montreal track in 1978, on what to me looks like (bias ply) SLICKS, even though the commentator (Murray Walker) sais they are rain tires.

He is indeed on rain tyres, you just don't see it from the low quality youtube video. The grooved tyres are very apparent on the dvd.

http://koti.mbnet.fi/zoic/random/MontrealDepaillier.jpg

[Roland Ehnström]

Thanks, I need to get that DVD!

[Roland Ehnström]

To be honest, while that is a good clip, it looks like he was going pretty
slow to me, at least compared to today's speeds. Also, he may have had full ground effects with side skirts, too.

Canada
Fastest Lap 1978: Alan Jones 1'38.072

Canada
Fastest Lap 2005: Kimi Räikkönen 1'14.384

Of course they were going slower in those days, MILES slower! The cars had so much less grip in every possible way, especially in tires and aerodynamics, and they had less than 500 hp compared to almost 800 today. (And that Tyrrell didn't have ground effect, only Lotus had ground effect in 1978.)

But the point I'm trying to make is that high SPEED doesn't in itself provide good racing. In fact, I think F1 cars today are even a bit too fast to provide good racing and a good show. They're even so fast in the corners that it sometimes looks completely unrealistic. With lower cornering speeds, drivers could easier run side by side. With longer braking zones, drivers could easier outbrake another car. With less downforce, awesome bends like Eau Rouge, 130R, and so on, could not longer be taken flat out, which would make them much more challenging again. With lower cornering speeds and higher slip-angles (bis ply tires!), the audience and TV-viewers could easier see what the drivers do, and why. And so on...

[zoic]

That lap, and many others are on "Lap of the Gods" DVD.

Bought mine from http://www.dukevideo.com

[checkered]

But the point I'm trying to make is that high SPEED doesn't in itself provide good racing. In fact, I think F1 cars today are even a bit too fast to provide good racing and a good show. They're even so fast in the corners that it sometimes looks completely unrealistic. With lower cornering speeds, drivers could easier run side by side. With longer braking zones, drivers could easier outbrake another car. With less downforce, awesome bends like Eau Rouge, 130R, and so on, could not longer be taken flat out, which would make them much more challenging again. With lower cornering speeds and higher slip-angles (bis ply tires!), the audience and TV-viewers could easier see what the drivers do, and why. And so on...

I quite agree

about the point you make about speed. It's not absolute, but making the most of what you've got. How the resources should be distributed, acquired and limited to allow F1 grow and evolve in sustainable, relevant and exciting (i.e. fun) ways requires teamwork, alertness, knowledge, experience and wisdom ... it cannot be gotten "right" by definition. In such an environment ulterior motives backfire quickly. Whether F1 is "too" fast now, I don't know ... the FIA looks set to preserve this pace, so obviously they think it's appropriate for some time to come.

The F1 concept in its meaningful form is a hard sell by the way of words themselves. Motorsport can only really be understood with facets of intelligence other than the verbal one alone - it's a comprehensive experience. Add a variety of adjectives between "high" and "speed" and it can easily sound more like a list of excuses rather than an exercise in excellence. The cornering ability of the contemporary F1 cars does seem to defy common sense, but I'd slightly challenge the notion of engineers being resourceful beyond their own good. I suggest TV technology and track design lagging behind in the learning curve at least sharing some of the (perceived) blame here. Spa, fortunately, is very special with today's cars as well ... only the nature of the engines requiring a rev limit takes the edge off.

Tyre technology is on the verge of major changes as well. Contrasting bias and radial ply, even only hypothetically, goes a long way in considering what's good for F1 when it comes to upcoming considerations in this field. Power slides, I'm afraid, are not very well in line with "green" ideals that have to be taken into account, nor technical relevance. But is there another way then, to recapture a certain element of "living in the moment", intuitive, body-conscious and acrobatic driving? Rallying, it seems, hasn't lost this one bit.

[rjsa]

First thing, thank you all very much for the lecture. Now a somewhat related question:

It seems to me that F1 tyres have a much highier profile than the top street tyres (as low as 30 or 25). Is that ruled or some other factor will mandate the present construction?

[zender05]

Modern F1 cars have very limited wheel travel. To compensate for ridiculous spring rates, they use higher profile tires.

Wheel travel is limited because of the regulations stating that downforce producing appendages must be attached to the frame.