A quick review of information from selected manufacturers' websites reinforced some fundamentals on this subject.
>From Michelin: "The finer the thread the higher the density. It is an important characteristic of a light, supple and fast tire. Higher density is not always better; it must consider strength, durability, and real world situations to provide optimized performance." Schwalbe points out another discrete fact in description of construction: "The carcass is a rubberized textile fabric which is laid around the bead cores. The carcass is then coated with a rubber compound. The tire tread is applied and the assembly is vulcanized." The compound coating the thread cloth matrix complicates things immediately. Vittoria: "Cotton is the traditional material used for high quality tubulars. Vittoria produces all its casing products in-house with a wide range of cross-sections, from natural cotton to 220 TPI for its tubular range. A fabric made from finely woven thin yarns to get a softer and more flexible casing offering amazing grip thanks to greater contact surface with the road. Better comfort too, as micro impacts are absorbed better. Plus faster speeds, thanks to better rolling resistance. The density of the fabric is expressed in threads-per-inch (TPI): the higher the TPI, the finer the threads and the denser the weave. The higher the TPI, the more flexible the tire. Cotton is incredibly tough and fine, letting us produce casings with the highest possible TPI." Maxxis, regarding TPI measurement, offers: "The number of nylon threads that cross through one square inch of the tire’s casing. Lower TPI gives better puncture and tear resistance, but is heavier. Higher TPI conforms more to the terrain, offering a smoother, more supple ride. It is also lighter weight. Maxxis TPI ratings are the threads-per-inch of a single casing ply, as compared to some competitor TPI ratings." Summing up key points from these general corporate sources: 1) TPI varies and increases the suppleness of comparative fiber cloths (cotton, silk or nylon), but reduction of individual fibers' size may not be appropriate in every circumstance and the actual material of the fiber can have input to the ultimate perception of the casing suppleness. As Maxxis points out, some makers may be counting the threads of several layers of cloth which offset the threads to create a very dense effect but not from a single ply (actually illustrated on Vittoria's website). Among similar fibers there are levels of quality also; cotton can be graded in terms of the staple or individual fiber length as an example. 2) The make up of the compound applied to the matrix the thread casing provides has an important role in the outcome of the tire's characteristics. Clearly a tire's intended end use will dictate the outcome product somewhere on the spectrum between durability and suppleness. Each maker lays claim to a balanced, innovative solution to that problem with lots of copyrighted nomenclature. 3) The tread cap (and any puncture proofing sandwiched beneath it atop the carcass), and its compound make up, has impact on product ride characteristics, the same true for the decision and compound used to "gumwall" the tire versus leaving it a "skinwall" tire. That's a handful of parameters that encompass several features of tire construction to consider when putting a finger down to say "this is the one" when tire shopping. My hat is off to the developers and designers who specify all of these parameters, designing a tire that will find an audience of consumers who can discern its performance and differentiate it from others enough to justify its expense and distribute it widely enough to reach their buyers in the marketplace. Andy Cheatham Pittsburgh -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en-US. For more options, visit https://groups.google.com/groups/opt_out.
