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[expeditionswest]

Sean K. previously said:

Of course you don't think it overly simplistic....you wrote it.

And having authored it, would I not have the clearest vision of its intent and its intended audience? You are confusing simplistic with a narrowed (pun intended) editorial focus.

Sean K. previously said:

The fact is and you admit: it's a very narrow use article. It was intended for expeditionary vehicles.....this is not an expedition only site and my comments were directed to those who are going to use their vehicle for more than just expeditions that might read this thread.

Absolutely, which was the point of my reply. My paper is intended for a narrow audience, but in reality, the concepts apply to the vast majority of fourwheelers. The majority of FJ owners are not hard core rock crawlers. They drive moderate trails, go camping, take road trips, vacation in Baja, etc., all functional requirement of an expedition specification.

You use specific arguments that my article does not address key concepts you believe are important to overall tire performance (and they are very important). You specifically say "he doesn't even seem to acknowledge", "it doesn't give an accurate depiction", etc. which is an argument against my paper in areas of theory that I specifically avoided due to time and the intended topic constraint.

We can talk for a year on this forum about tires, their construction, air pressure, carcass construction, etc. My article was specifically about section width and I clearly state that, so to say that is is overly simplistic or doesn't give an accurate depiction is only because the article does not address topics, applications or variables that I specifically omitted due to scope.

Sean K. previously said:

I've talked with Gary Enterline at BFG....the guy responsible for the best adhesion rockcrawling competition tire ever produced and he chose 12.5 for the section width. I don't think he considered that "overly wide", nor was it what "marketing" dictated. He picked what worked. I do completely understand your point that rockcrawling man made or natural courses or trails is completely different than expedition use....to an extent. However, traction is traction. You either make it up an obstacle or you don't. You'd be niave to believe that the two areas of 4wheeling don't ever encounter the same type of terrain or traction requirements regardless of it being Florence Junction or elsewhere.

Do not assume for a moment that I am naive (I can't help but see the irony in your misspelling of an insult to someone's experience) about this topic. Why use personal attacks in an effort to bolster your argument?

Glad to hear you have spoken with Gary. I consult with Michelin engineers and have been sponsored by Michelin/ BFGoodrich for many years.

The Krawler is specifically designed for rock crawling. My article is about driving a heavy vehicle for long distances over infinitely variable surface conditions.

My point is clearly that rock crawling is a highly specialized activity and has 20% of the functional requirements of a vehicle/tire that will travel around the world, through countless terrain variables. In my travels in Mexico and the Southwest, I encounter rocks all the time. I have crossed hundreds of miles of rocks in Algeria and Morocco, etc. I have driven expedition prepared vehicles countless times over the Rubicon, etc. Rocks are absolutely a design consideration when selecting a tire for overland use, but it is only one variable.

Sean K. previously said:

As I said in my first post.....I agree with much of your theory. I find you to be correct that narrower tires (10.5-12.5) are the best fit for most vehicles for MOST applications (not necessarily expedition use).

Yes, you did acknowledge the diminished returns....I overlooked it. My apologies. I do have to wonder though: how did you determine that the sweet spot for the GVW of the FJC is 10"? Why should we believe your numbers over anyone else's? What constitutes your "90% of trail conditions"? I'm pretty sure that 90% of my trail conditions would be different than your's. Where'd you get the number?

It is based on the GVW of the FJ. GVW is a known variable and saves much of the complexities (and impossible cost) of testing every possible 4wd. In my testing with Michelin, Jeep and the US military we have conducted countless hours of pressure variation testing, surface imprint and shear testing, road handling, etc.

The majority (lets use 90%) of trail conditions are a set of known functional requirements, which can be replicated in testing, like at the Nevada test center, etc. (where the Jeep "Trail Rated" performance testing is conducted). There are obviously deviations from test environments to different geo regions and conditions, but the performance expectations can be pretty clearly tested, at least from one tire to the next.

Again, my article and the vast majority of tire testing is not about highly specialized rock crawling, but mild to moderate trail use, road use, highly variable surface conditions like mud, rocks, decomposed granite, shale, hill climbs, NVH, etc.

If you want to talk about rock crawling with 35" tires and tube chassis buggies, feel free to do so, but do not make your argument about my article, which is intended for a different audience and requirement.

Sean K. previously said:

Again, you say it's not overly simplistic, yet you leave out the number one factor (air pressure) that a vehicle owner can manipulate to make a difference in how his tires perform. That doesn't make sense to me. Do your theories about 10" on an FJC being optimum for 90% of trail uses hold up if we do change the air pressure varaible? What if we add beadlocks and really start dropping down into the single digits?

You leave out construction and compound, when HUGE strides are being made in these areas to come up with the ultimate tires for traction? Again, overly simplistic, IMO. I realize you tried to narrow the scope.....but the fact is: the topic of tires is too dynamic to leave out other vital areas to a tire's performance to solely focus on one area alone. These areas are all inter-related and cannot be seperated if one is hoping to get a full, accurate picture. Yes, the major components can be examined individually, but not without a context.

Sean, have you ever written a white paper, or participated in an engineering review resulting in a white paper? If you have, then you know that the intent of a white paper is to state a position, to identify results of specific testing, etc. A white paper is not intended (they never have been) to be inclusive, but to promote discussion, interest and further research.

I am not discounting that air pressure is even MORE important than carcass width or section width in many trail environments. That is known. There is also no question that carcass design and construction play major roles in performance.

I make that overwhelmingly clear in the paper, which is two tires OF THE SAME CONSTRUCTION and THE SAME HEIGHT and THE SAME AIR PRESSURE but with a change in the variable of WIDTH. For a reader to assume that a white paper cannot be written with the intention of reviewing the performance variable of WIDTH only, then perhaps it is not the paper at all that is "overly simplistic"...