Camber V.S. Straight-Line Speed

[bill shoe]

Someone page for JET please

Anytime JET wants to chime in on tire issues or anything else I'll be happy to read it. However, we can still think and research in the absence of JET.

[strad]

Since when did Wiki become a trustworthy source?

[HampusA]

More camber - longer braking distances due to a slightly smaller contact patch.

As far as a higher top speed goes i think that a few degrees of tire angle is quickly eaten up by mother nature as you go faster and faster.

Taping up every crack on the car will be more effecient.

[Jersey Tom]

Energy loss (RR) isn't about how much tread you have in contact with the ground. It's about how much rubber you have, the material properties, how much it's stretched, and how many times a second.

So let's assume a cambered tire gets rid of some footprint area. If the camber is now deflecting some portions more and some less, it could be a wash.

I'll be honest though I don't have much feel for representative behavior in this area.

[xpensive]

Comparing with a roller-bearing, in a perfect rolling contact, with no slipping present, the resistance comes from the hysteresis in the material itself, the difference between the energy it takes to elastically deform an object and what is returned when the material re-takes it shape, like a valve-spring. This difference in energy is converted into heat in said object.

For a tyre, this should be pretty much regardless of camber I think, either more deflection over a smaller patch or vice versa?

Micro-slip between rubber and road is a different matter however, perhaps a smaller contact-patch could help there?

OT:
In case of a roller bearing, much of the energy is lost through viscous resistance in the lubricant, why a wider bearing loses more.

[munks]

My opinion, based on graphs that I remember but can no longer locate, is that the effect is probably tire and condition dependent. IIRC, in a graph of camber vs. rolling resistance at different loads, there were typically local minimums, but they were different at different loads. And they were biased to one side (+1 degree had lower rolling resistance than -1 degree), possibly compensating for some plysteer or conicity of the tested tire.

Using Google just now comes up with similar trends for wheelchair tires: http://www.rehab.research.va.gov/jour/8 ... Veeger.pdf

So currently I don't think there's a general rule of thumb here, I think the tire would have to be tested for the expected conditions.

[raymondu999]

I don't think it would affect much, would it? I don't know exactly, but when NASCAR races on ovals, don't they run extreme negative cambers on the outside tyre and positive camber on the inside tyre JT? I don't know though.

[Jersey Tom]

I don't think it would affect much, would it? I don't know exactly, but when NASCAR races on ovals, don't they run extreme negative cambers on the outside tyre and positive camber on the inside tyre JT? I don't know though.

Correct on direction of camber. Not sure what you're getting at though.

[raymondu999]

My point being straight-line speed is also very crucial on ovals, is it not?

[timbo]

I always felt camber is used to aid cornering by providing bigger contact patch in roll.

[strad]

I always felt camber is used to aid cornering by providing bigger contact patch in roll.

Yep...That's the reason for the short track settings that were mentioned. In the corner that tire that is leaning way over on the straight, is standing straight up mid corner.

[Jersey Tom]

My point being straight-line speed is also very crucial on ovals, is it not?

Sure. But what's going to get you more speed on a straightaway... getting more speed through the center of a corner, or playing with rolling resistance?

[xpensive]

I wonder why some members have such a problem with sticking to the issue here, which is if camber affects rolling-resistance in a straight line?

At least that's what this here thread's title says?

[Jersey Tom]

Well who the hell knows. Meaningless hand waving without data.

[bill shoe]

Staying on topic--

Everyone is still directly discussing camber and rolling resistance. Is it really so bad if the discussion veers (pun) from straight-line to corners? Seriously, camber vs rolling resistance is still relevant around corners.

Technical issue--

At NASCAR tracks like Daytona and Talledega I think the cars go WOT all the way around relatively easily. The thing that seperates a good vs bad car is how much resistance they have doing this. Resistance comes from air drag and tire resistance (also powertrain drag, etc. but ignore that here). So a chassis engineer needs to focus on getting the car around the track while optimizing some combination of:

1. dynamically positioning the car into it's lowest air-drag state,
2. minimizing longitudinal tire resistance during cornering and straight-line running.

I would think that due to #2 there would be a lot of detail knowledge about the exact amount of longitudinal tire drag at various cambers, slip-angles, and cornering forces. This knowledge would allow the chassis engineer to design a setup so that the four tires give the necessary lateral force in the corners with the least amount of longitudinal resistance. Perhaps this is the kind of knowledge that JT can't simply give out on a forum.