Camber Tires: Tires Get Tipsy

[zonk]

Found this article worth sharing:

http://www.automobilemag.com/features/n ... ewall.html

and producer page:

http://cambertire.com/indexretail.html

[Jersey Tom]

So they've gone and built tires with extreme conicity. Meh. I feel like it defeats the purpose of camber - at least in true performance cars. Great though I'm sure for guys who like to put extreme camber in their daily drivers and chew up inside shoulders while making grocery runs.

(The intent of camber on performance cars being IMO to preload the inside shoulder of the tire so that when it rolls out under cornering load, you have a nice big square footprint. By doing this conicity thing I'd think it gets eliminated)

[rjsa]

So they've gone and built tires with extreme conicity. Meh. I feel like it defeats the purpose of camber - at least in true performance cars. Great though I'm sure for guys who like to put extreme camber in their daily drivers and chew up inside shoulders while making grocery runs.

(The intent of camber on performance cars being IMO to preload the inside shoulder of the tire so that when it rolls out under cornering load, you have a nice big square footprint. By doing this conicity thing I'd think it gets eliminated)

My thoughts exactly. And not having a reference on how hard the rubber is pretty much voids any comparison to other tyres.

[Tim.Wright]

(The intent of camber on performance cars being IMO to preload the inside shoulder of the tire so that when it rolls out under cornering load, you have a nice big square footprint. By doing this conicity thing I'd think it gets eliminated)

Interesting theory. So is this basically what you think are the mechanics behind the term "camber thrust", or do you consider that as coming from a different effect? So basically, are you saying, is that the extra grip from to camber angle is due to having a larger contact patch, and not necessarily due to extra elastic distortions?

What you typically read in literature is that the camber thrust effect is due an extra lateral distorsion in the contact patch which comes from the tread elements having to change trajectory w.r.t the wheel centre as they enter the contact patch. Not a great explanation, but I'm sure you know what I'm talking about since its written in a lot of books.

[Jersey Tom]

You can get "camber thrust" in the linear range, and at the same time zero gain (or even a loss) in the peak traction range. Two totally different concepts.

[olefud]

What you typically read in literature is that the camber thrust effect is due an extra lateral distorsion in the contact patch which comes from the tread elements having to change trajectory w.r.t the wheel centre as they enter the contact patch. Not a great explanation, but I'm sure you know what I'm talking about since its written in a lot of books.

Ditto TJ. Greater thrust comes from greater contact area, all other things being equal. If more thrust is desired just point the wheel a bit more into the turn. The general rule is to add usually negative camber until the tire shows an equal temperature profile across the tread.

Having elements -I assume this means a portion of the tread- progressively change trajectory seems to suggest an asymmetric contact patch loading which would decrease traction.

[Tim.Wright]

This is what I meant when I was talking about tread elements in the contact patch changing trajectory. Tread elements on a free rolling vertical tyre describe a circle constrained to a plane. When you add camber, this theory says that the tread elements are deflected out of the plane when it contacts the ground.



In the end, i.e. in tyre data, you only see the net effect which is more camber = more lateral force (obviously up until a point). It would be interesting to know how much comes from the elastic theory above and how much from the contact patch size theory of if indeed one of both of these theories are BS.

Actually, I just had a thought... This elastic deformation theory would explain camber thrust in the linear region. It is essentially deflecting the tread elements more than what you would see from slip angle alone. But fundamentally, its mechanics of producing grip are the same as that of lateral slip angle (which is also just a progressive deflection of tread elements in the contact patch).

At the limit however, these camber induced lateral deflections would be small compared to those coming from the slip angle so the effect would be almost insignificant. Add to that the fact that when the tyre is laterally saturated, adding more lateral deformation in the contact patch wont give you more grip. This means that the extra peak tyre force must be coming from another effect, i.e. a better contact patch.

...anyway quite an interesting discussion. Its why I hang around this forum. Once a year, I learn something really useful.

[Tim.Wright]

Oh and regarding the original post with the conical tyres. I think we could safely say that these tyres destroy the camber thrust effect coming from both the elastic deformation theory and the contact patch size theory.

I think the main point of them is to allow you to continue around with your camber at -5deg, looking like a penis, but without the extra tyre wear. Quite a noble cause.

[Paul]

Those are exactly my thought on the subject. As I see it, you can gave as much "camber thrust" as you wish, but you're not taking the corner unless you have the grip level (read contact patch) to use the tarmac as a "spring board" of sorts to change vehicle's direction.

[Jersey Tom]

I think the main point of them is to allow you to continue around with your camber at -5deg, looking like a penis, but without the extra tyre wear. Quite a noble cause.

My sentiments exactly!

[zonk]

[youtube]http://www.youtube.com/watch?v=Z5bT4hJ4B6M[/youtube]

[ubrben]

He didn't back off the tyres on the same car...

Ben

[rjsa]

That's a lesson on scientific methodology: Not a single stop watch involved in a speed comparison. =D>

[Tommy Cookers]

normal camber in trackday use causes wear on the outer third or outer half of the tyre
camber tyres would solve this problem ie give even wear and longer life in such use
(using normal camber, they would be installed the opposite way round to that presumably intended, is this a problem ?)

also, I'm guessing that they are made from a grippier/less durable rubber compound than usual ?

[thepowerofnone]

Camber thrust is only part of the gain of camber: its widely accepted that the two key features of a tyre's grip are elastic deformation and chemical adhesion to the road surface. Camber thrust is an affect of the former - the tyre can be forced to deviate further and induce a higher slip angle without a gain to slipping. The increased contact surface helps with providing a larger contact patch and therefore a greater adhesion surface. Both interpretations are correct.

And a car which is wearing the outside shoulder excessively isn't ideally set up (from the perspective of camber alone), although I agree with the comment that this is how the majority of cars are forced to run for the purpose of compromises. It does seem like an unnecessary complication to tyres however, if everyone runs the same tyre wheres the issue - most serious classes run standardised tyres and unless this company pumps big money into some race classes as a title sponsor I can't see this taking off. Tuning with these tyres would be a hassle, you would almost certainly still want to run some form of camber (not all tracks are going to suit on tyre shape) and that could well produce unwanted wearing: running positive camber on these would be a nightmare. It has some genuine advantages, but the complications of manufacture would likely be prohibitive to mass consumer market (not to mention trying to fit those tyres to the vast majority of road cars which run a fixed camber).