I think it was Scorpion6 who asked the question, and that hsi question was (exactly): "Any advantage of the assymetrical tires over the symetrical?" [/b]
Which included pictures of a tire tread pattern with an asymmetrical tread pattern. How did you ascertain that he was asking about asymmetrical construction when tread pattern was the obvious question?[/b]
The obvious question was not about tread
pattern. He asked about asymmetrical
tires, not about asymmetrical tread patterns. Asymmetrical construction is the steak, and the tread pattern is merely the sizzle. For a lot of marketing people (maybe you are among them, maybe you are not: you tell me) appearance is more important than substance; it's all about bling. In my earlier (October 10) post, I indicated that I thought that the steak was more important than the sizzle, that the substance was more important than the bling.
I do not know of any asymmetrically constructed tire that does not have an asymmetrical tread pattern, but there are symmetrically constructed tires that have asymmetrical tread patterns While the asymmetrical tread patterns do no harm, and may actually provide some benefit (like the spoiler wings on the back of econobox cars), the real benefits of an asymmetrically constructed tire are under the skin, not confined to the tread. So IMHO a proper response to Scorpion6's question about the advantage of an asymmetrical
tire ought to concentrate on what is important, not on the cosmetics.
While I'm sure Pirelli has had their share of innovations, I don't agree with your opinion that they are the LEADER
[/b]
The word "leader" is yours, not mine. I wrote, "Pirelli has managed to stay at or near the top in coming up with an edge in tire technology." Not worth arguing about.
Let's start with Toyo:
Toyo continues to innovate in winter tire technology with the use of finely ground walnut shells
[/b]
I believe that that innovation (dating to the 1970s, actually) came from the retreading operation of one of Toyo's largest customers, Les Schwab Warehouse Center, Inc., headquartered here in Oregon, with whom I have <ahem> more than casual familiarity.
I would consider Goodyear to be a leader in materials use. They were first to introduce multiple compounds across the face of the tread and they have been innovative in the use of Kevlar, aramid and most recently, carbon fiber [/b]
I, too, consider Goodyear a leader in materials use. Incidentally, aramid and Kevlar are not two different materials. Goodyear and Dupont jointly developed aramid, at that time code-named Fiber B, a few decades back. Originally, aramid was developed
specifically as a tire fabric, intended for use both as a carcass material and as a belting material. (In fact, it is superb in both applications, but, from a marketing standpoint, it was an initial failure: consumers got all stary-eyed about
steel-belted radials, and the first aramid-belted radial tires may as well have been nailed to the tire showroom floor. Aramid, which is not cheap, also proved difficult to work with on a tire production line, and so it all but disappeared from view in automobile tire construction, though it long has been a staple in high-performance bicycle tires.) Dupont designated its aramid Kevlar, and, IIRC, Goodyear called its aramid Flexten. When aramid flopped initially as a tire material, Dupont sought out new uses for its baby, and eventually came up with relatively lightweight "bulletproof" (well, protective, anyway) body armor. The cachet that then developed around "bulletproof" Kevlar helped the marketing when later forays were made to incorporate aramid in automobile tires. I notice that, although Goodyear has its own brand of aramid, it advertises the ResponsEdge as having a Kevlar® layer under the steel belts.
Btw, you mentioned that Pirelli offers run-flat technology over a wider range of tires than anyone else. However, Pirelli's own website only lists the
[email protected] as run-flat and TireRack only lists 4 other lines with RFT (total of 5 lines). Goodyear, by constrast, offers its EMT technology on the following products:
Eagle F1 GS-D3
Eagle F1 Supercar
Eagle F1 GS
Eagle F1 GS-2
Eagle GS-C
Eagle GS-D
Eagle F1 A/S-C
Eagle RS-A
Eagle NCT5
Eagle Ultra Grip GW3
Maybe I'm misinterpreting your statement or something, but it would appear that Goodyear offers a wider variety of run-flat choices. TireRack shows
12 run-flat lines for Bridgestone (2
more than Goodyear)!
[/b]
I don't think you are misinterpreting my comment so much as overlooking one important word: "types." I wrote "Pirelli also has run-flats over a wider range of tire types than any other tire maker I am aware of." For instance, Pirelli has run-flat winter tires and run-flat off-road tires. I am unfamiliar with the GW3 tire you mantioned, but the other Goodyear tires you cite are all conventional passenger-car tires, most of them summer tires.
I have my doubts about the true benefits of the asymmetric construction you're so excited about. If the two different sidewalls don't flex at the same rate, I predict Goodyear will have irregular wear problems[/b]
The carbon fiber sidewall insert is only one of the asymmetries of the Goodyear ResponsEdge. In another context, you mentioned another when you wrote: "They were first to introduce multiple compounds across the face of the tread." The ResponsEdge has an all-season tread compound on the inside of the tread and a summer compound on the outside part of the tread.
The inner sidewall and the outer sidewall of a tire -- especially the outside tire when cornering -- are called upon to perform different roles under cornering forces. Not knowing more about the specific Goodyear tire, I cannot tell whether performance considerations as such suggested the use of an insert. My
guess (it is only a guess) is that Goodyear wanted a very soft-riding tire for the market segment the tire is aimed at, which can be achieved partially by making the sidewall very flexible. However, an overly flexible sidewall is in danger of rolling under when subjected to lateral forces, so (my
guess) Goodyear added the carbon fiber insert to keep the tire fron squishing down to the rim in tight turns. Because the cornering forces apply much more strongly to the tire on the outside of the turn, there was no need to stiffen the inner sidewall of the tire, and it could be left very flexible to absorb bumps in normal driving. (The preceding is only a guess, but it illustrates the additional degrees of freedom handed to the engineers who design tires when they can determine in advance which side of the tire will be on the outside and which on the inside.)