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ralph124c
11-22-2009, 10:36 AM
Michelin makes a big fuss about their computer-designed tread designs-they claim that their advanced tread design makes their tires better than everybody elses. Is this true? I don't see how (after almost 100 years of auto tire manufacturing) that there could be anything new in tread designs.
Tires (above a certain price point) look pretty much the same to me-is there anything magical about those squiggles and saw-tooth patterns that make expensive tires better? or is it mostly advertising? Why is it that some motorcycle tires have such plain tread designs (just straight ridges)? surely they need traction more than cars do (two wheels vs. four).
And those asymmetric tires that were big a few years ago(you must use one design for the left side, another for the right-no mixing)-was there any proven benefit to these (aside from bigger profits for the tire store?):confused:

enipla
11-22-2009, 10:59 AM
Not sure about the computer designed aspect, as I am pretty certain that all tires are designed on a computer. And probably tested that way as well. At least to a degree.

I will say that there is a huge difference in tires even within the same manufacturer. And brand and type. And the material that the tire is made of. Thatís a biggy.

I think it comes down to figuring out what you need. And that can be tough. I live in ice and snow. Since I get home before my Wife (and plow), I run a tire that is a bit better for deep snow just so I can get home to my plow truck.

My Wife gets set up with more of a regular snow tire.

Iím constantly looking for the right tire. I buy a new set every two seasons. Mileage be dammed. If they get below half worn, itís time to replace them (for me, Let it snow let it snow)

Bryan Ekers
11-22-2009, 11:18 AM
Science is indeed involved. However, it is the science of psychology and marketing.

enipla
11-22-2009, 11:53 AM
Science is indeed involved. However, it is the science of psychology and marketing.Are you saying that there is no difference between different tire designs and manufacturers?

I doubt you are. Of course there is marketing involved. There is also science.

Differences in what different tires can and should do is quite remarkable.

Even if they are in the same series or class.

Stranger On A Train
11-22-2009, 12:32 PM
Science is indeed involved. However, it is the science of psychology and marketing.Such a thoughtful, informed response. I take it you have intimate functional knowledge about the engineering analysis and testing that goes into evaluting the environments and capabilites of automotive tires?

To the o.p.: tires are one of the most highly engineered components on an automobile, right after transmissions and suspensions. More engineering effort is devoted to tire performance than to engine performance or active safety systems, and the science and technology of tire capability and manufacturing process is under continual revision. Many of the same chemists who work on tire elasomer formulation have also worked n solid rocket motor grain design and development.

I can write in greater (possibly tiresome) length on this topic, but only if it is of interest. After all, I wouldn't want to be called out for being neglectful to the predominant psychologcal and marketing aspects of tire manufacture.

Stranger

BrandonR
11-22-2009, 12:34 PM
Michelin says they employ 888 people (http://www.michelin-us.com/north-america/future/) at their R&D center, most of which are engineers. I doubt they'd spend that kind of money and effort if it was just "all marketing." It also says they created the "first 80,000-mile passenger tire for American-made vehicles," something I doubt would be feasible without complex simulations and computer modeling. Sure, some of it is marketing (what product isn't?) but to say it's all the same, I'd disagree.

astro
11-22-2009, 12:42 PM
Interesting ... I can find almost nothing on the science behind tire tread design on the web, yet I would imagine it has to be a pretty well developed science and body of knowledge at this point.

Here's a good and fairly detailed overview of tires (http://www.offroaders.com/tech/AT-MT-Tires/tire-tech.htm)

Here's some general comments about the functional aspects of various tread designs. (http://www.tpub.com/content/engine/14081/css/14081_75.htm)

Sam Stone
11-25-2009, 03:56 AM
Michelin says they employ 888 people (http://www.michelin-us.com/north-america/future/) at their R&D center, most of which are engineers. I doubt they'd spend that kind of money and effort if it was just "all marketing." It also says they created the "first 80,000-mile passenger tire for American-made vehicles," something I doubt would be feasible without complex simulations and computer modeling. Sure, some of it is marketing (what product isn't?) but to say it's all the same, I'd disagree.

And Gillette spent $750 million on R&D to develop the Mach 3 razor.

The razor is a decent analogy. It's both marketing and real engineering. The Mach 3 was a demonstrable improvement over the razors that came before it. But it was definitely an incremental improvement, and the research costs are not so much driven by the shortcomings of previous products, but by the need to innovate and build up fresh patents as the old ones expire, even if huge dollars have to be spent for modest improvements.

This is short-changing tire R&D a little, because there's a hell of a lot more going on in a tire than in a razor, and there's lots of room for engineering and materials innovations. Rubber compounds, belts, sidewalls, treads, you name it. I remember reading a road test in one of the car magazines where they took some muscle cars and put them on their original tires, then took the same cars and put them on modern tires. The difference was astounding. The new tires made the cars completely different in road feel, driving comfort, cornering ability, and start/stop traction.

Isamu
11-25-2009, 05:43 AM
It's definitely not all marketing. Tires and tire designs are indeed very complex areas. I am by no means an expert, but in the last couple of years have been partially involved in the patent work centering around the design of automobile tires.

A tire manufacturer does not start out a new model of tire by first creating an advertising campaign for the tire. No, it's always from the other end - the researchers. They are constantly coming up with new and (demonstrably) better designs for different conditions and different requirements. In fact it's quite exciting to read about the new models that will be coming through and how very small changes to tread patterns or dimensions have been shown to increase traction in dry, decrease planing in wet, etc.

JFLuvly
11-25-2009, 09:31 AM
Why is it that some motorcycle tires have such plain tread designs (just straight ridges)? surely they need traction more than cars do (two wheels vs. four).


The idea is to keep more rubber on the road, less holes equals larger contact patch. The channels are to channel water away and keep rubber on the road. Race car tires are usually grooveless, which once again leads to a bigger contact patch which equals more traction.

Back in my big boy plays in the mud days, I upgraded to a set of 35 inch BF Goodrich Mud Terrains. The difference was remarkable as they are designed to throw the mud out of the grooves. This keeps the knobs clean to allow them to bite better, as oppsoed to lessor tires that will clog up and bocome slicks.

Chris Luongo
11-27-2009, 02:05 AM
I can write in greater (possibly tiresome) length on this topic, but only if it is of interest. After all, I wouldn't want to be called out for being neglectful to the predominant psychologcal and marketing aspects of tire manufacture.

Stranger

Stranger, I'd love to read anything you have to contribute. I've always been very interested in tires.

It's clear to me that all tires are not the same---I've had replacement tires installed on cars that were vastly different than what was there before.

I think the OP does have one point, though: Tire sales materials will rarely tell you the tire's weak points. You rarely see something like "Our tire Model A handles well but is too noisy; buy it if you drive fast. Our tire Model B is quiet and comfortable but has sloppy handling; buy it if you drive like an old lady."

Rhythmdvl
11-27-2009, 12:44 PM
I find it bizarre that tire pressure is dictated by the automobile manufacturer -- that the proper inflation pressure (or so I've been told) is on the door jam, not on the tire sidewall. Maybe I should ask about this in GQ ...

Stranger On A Train
11-27-2009, 01:13 PM
I find it bizarre that tire pressure is dictated by the automobile manufacturer -- that the proper inflation pressure (or so I've been told) is on the door jam, not on the tire sidewall. Maybe I should ask about this in GQ ...The optimal tire pressure isn't just a function of the tire construction, but what and how loads are applied upon it. The tire manufacturer basically specifies a range of tire pressure and what applications or conditions modify it, and the vehicle OEM dictates to the customer what their engineering determines the tire pressure to be. It is the same with all other components on a car.

I'd be willing to go into greater length upon tire design, but preferably in General Questions or as a response to a Mailbag question. The modern automotive belted radial tire is one of the most complex single-mechanism devices ever designed and performs a number of different functions, including being an inherent part of suspension dampening, braking response, and vehicle safety.

Stranger

DangleYourModifier
11-27-2009, 01:29 PM
I have a friend who is a development driver for BMW. What that means is he drives the new cars as they come into the country and decides how they will be set up for our conditions. Things like shocks etc. A BIG part of what he does is decides which tyres the car will be sold with (as our road and weather conditions are very different from Europe.)

astro
11-27-2009, 01:32 PM
The optimal tire pressure isn't just a function of the tire construction, but what and how loads are applied upon it. The tire manufacturer basically specifies a range of tire pressure and what applications or conditions modify it, and the vehicle OEM dictates to the customer what their engineering determines the tire pressure to be. It is the same with all other components on a car.

I'd be willing to go into greater length upon tire design, but preferably in General Questions or as a response to a Mailbag question. The modern automotive belted radial tire is one of the most complex single-mechanism devices ever designed and performs a number of different functions, including being an inherent part of suspension dampening, braking response, and vehicle safety.

Stranger

I'm probably searching with the wrong keywords, but why does virtually none of this extensive engineering and research on this complex mechanism appear to be available on the web? Is it all proprietary corporate information.

gonzomax
11-27-2009, 02:13 PM
With computers every possible permutation of tire design can be done in a week. Tread patterns have been experimented with for decades. There is nothing new. Testing improves and data collection is enhanced so decisions about what is best can be determined. A lot of testing is track testing. I had an uncle who drove around tracks for Firestone. Racing tires are different.But passenger tires are not that different.

Stranger On A Train
11-27-2009, 02:51 PM
I'm probably searching with the wrong keywords, but why does virtually none of this extensive engineering and research on this complex mechanism appear to be available on the web? Is it all proprietary corporate information.A lot of the details on tread design and tire composition are proprietary; however, the reason that you probably can't find much on the Internet with regard to the analysis and development of automotive tires is because it's just a pretty specialized discipline that isn't of general interest even for the engineering community. Unlike a field like metallurgy, aeronautics, or energy conversion, it is neither especially useful to design engineers at large, nor sexy enough to popularize to the general technophile contingent. There are really only a handful of academic institutions in the United States that devote significant research into all facets of automotive design and research (University of Michigan, Michigan Tech, Ohio State, Virginia Tech) so it's not an enormously popular subject.

Thomas Gillespie's Fundamentals of Vehicle Dynamics (http://www.amazon.com/Fundamentals-Vehicle-Dynamics-Thomas-Gillespie/dp/1560911999/) has a chapter (Chapter 10) that gives just a flavor of the complexity of automotive tires. Hans Pacejka's Tire and Vehicle Dynamics (http://www.amazon.com/Tire-Vehicle-Dynamics-Hans-Pacejka/dp/0768017025/) has a more comprehensive explication of tire dynamics, but I don't have it in my collection (and haven't read the 2nd ed). However, I don't know of any handbook or text that is specifically devoted strictly to tire design and development; I just know several people who have worked in the field and have described in detail the type of analyses and testing performed, and the various SAE, FISITA, and JSAE publications I've read.

Stranger

Stranger On A Train
11-27-2009, 02:58 PM
With computers every possible permutation of tire design can be done in a week. Tread patterns have been experimented with for decades. There is nothing new. Testing improves and data collection is enhanced so decisions about what is best can be determined. A lot of testing is track testing. I had an uncle who drove around tracks for Firestone. Racing tires are different.But passenger tires are not that different.I find myself in awe of the radiance of your in-depth knowledge and expertise in the field of automotive engineering, tread design, and coupled multiphysics analysis codes using the most advanced techniques in computational fluid dynamics, explicit finite element method with hyperelastic materials, multi-body dynamics simulation, and nonlinear modeling of tribological interfaces. Please, Grandmaster, permit us to bask in the light of your extensive knowledge in this field.

Stranger

Malthus
11-27-2009, 03:16 PM
I'm no engineer, but I rather suspect that the main difficulties in tire design are that to an extent the desireable characteristics of tires under various road and weather conditions are simply incompatible, and making them compatible calls for extreme cleverness and high technology.

If a company could come up with an all-weather tire which really performed well enough on snow so that a Canadian like myself did not have to have a seperate set of specifically "winter tires" (and which performed equally well on hot summer roads), they could dominate the market.

Francis Vaughan
11-27-2009, 11:19 PM
Coming from another direction. The application of computers to design. Whilst marketing loves to latch onto anything to differentiate a product, and I doubt the other tire companies are not doing similar things, there is likely to be a big lement of truth to the claim.

Computers in highly complex mixed mode design and analysis have made astounding strides. It was not all that long ago that the common idea of computer aided design was an engineer sitting in front of a workstation designing something with a 3D CAD program. Were CAD was computer aided drafting. A fancy drawing package. Additional programs could be used to turn the output into something useful to a toolmaker. For a tire, the guy that crafts the moulds the tire is cast in. For a mould this may mean a toolpath creator, that can drive the NC mill that cuts the mould out of a billet of metal. None of this is really design.

Even manufactuing a tire is a very complex task. Something subject to a range of very messy and complex chemistry. Since tires are cooked in the moulds, manufucture is a diabolocal heat flow problem. Having very fine grained knowledge of, and better control of the exact time and teperature during the process makes a massive difference. This sort of thing is core business for high performance compute. The actual physical design of the treadpattern affects the heatflow, and the heatflow affects the final properties of the compound in the tread. This alone will affect treadwear and adhesion properties.

Then you get to the dynamic properties of the tire on the road. This is also an extraordinarily messy mixed system involving dynamics of the tread, dynamics of the tire, heatflow, hydrodynamics of water though the channels, different surfaces, just to start. Being able to simulate such a system to a fine enough granularity is very computationally expensive. And that only got you to the point where you could see what was going on. Not to the point where you were in a position to usefully use the knowledge to improve things in a systematic manner. It is only recently that enough computer power has become available in affordable enough lumps that a lot of this sort of work can be done. In the high performance computation arena things have been moving faster then Moore's law. Why? Because the cost has been dropping along with increases in speed, and the threshold for being able to assemble enough compute to do really interesting things has arrived for more and more tasks. So high end compute systems have actually been getting more expensive, better value for money, in addition to being ever faster. When the top system in the Top500 has quater of a million cores it starts to get astounding. Michelin won't have a system anywhere near the Top-500. But they very well may a system that five years ago would have ranked in the top 50 largest compute systems in the world.

gonzomax
11-27-2009, 11:48 PM
I find myself in awe of the radiance of your in-depth knowledge and expertise in the field of automotive engineering, tread design, and coupled multiphysics analysis codes using the most advanced techniques in computational fluid dynamics, explicit finite element method with hyperelastic materials, multi-body dynamics simulation, and nonlinear modeling of tribological interfaces. Please, Grandmaster, permit us to bask in the light of your extensive knowledge in this field.

Stranger

Are you suggesting every design starts from scratch. There is no backlog of tread designs and testing to work from. Boy that would be hard to do. You guys are special. Reinventing the tire every time must be pretty tough. So you continually invent the wheel. Bravo.

JThunder
11-28-2009, 12:48 AM
Are you suggesting every design starts from scratch.Nobody said such a thing. Nobody even remotely implied any such thing.

Rather, he was obviously responding to your statement, "With computers every possible permutation of tire design can be done in a week. Tread patterns have been experimented with for decades. There is nothing new." Are you seriously suggesting that anyone who contests that claim must logically believe that every single design is created entirely from scratch?