quote:If Tire Rack did the test, then I'll confirm that Tire Rack's test course does not use enough water to explore hydroplaning, which is where the V shape is supposed to work. But I should also tell you that the difference caused by the V shape is relatively small (my memory says that the value is 10% depending on the direction of rotation), which means the difference between a directional tire and an identical non-directional tire would be 5% - a value where some folks won't be able to tell the difference.
Originally posted by rpn453: I saw a test that was done where directional tires were run both forward and backward on a wet course to see the difference. I'm pretty sure it was Tirerack but I can't find it. Anyway, they couldn't tell the difference. But that was just wet pavement with no standing water. On standing water, I think a directional tire that clears the water out efficiently would make a big difference. The directional Michelin Pilot Sport A/S tires I got this year are more resistant to hydroplaning than any other tires I've ever used.
quote:Is the "saw tooth" you refer to the same thing as "feathering" which can be caused by high speed cornering? The very directional F1's I have, have always been rotated same side front to back and they are the quietest tires I have ever owned, even half worn or so (on smoother pavement mind you). I currently have 20k + on them and the are wearing just as even as can be. I rotate every 5K. Look into Nitto Neogen and Invo, Pirelli P Zero Nero M+S, and BF Goodrich. The tires on my truck feather because I like to drive fast in curves. I've seen brand new tires ruined (pursuit courses) due to feathering which was un-related to rotation issues.
Originally posted by VelociRacer: 2 directional tires I tried got noisy in the last half of its life. Toyo T1-S and more recently Kumho MX. Very noisy! So be ware. Non-directional tires, rotated properly, will not develop saw tooth, thus not get louder as the miles pile on. For my FWD car, I rotate with Forward-X pattern. Figure A in this page: http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=43 Figure D has to be the worst way to go in terms of tire life and noise level. I wish there were more ultra-high performance non-directional tires. I have AVON Tech M500 (3-season), Kumho ECSTA ASX (all-season) which I like very much. The M500 cleared water better than the T1-S but not as good as the MX. So there you go.
quote:Not so fast. Cupping is quite different, as it's an accumulation of 'random spotting' wear from worn or binding suspension parts (and possibly imbalance). Then one can have feathering or saw toothing across the tread (inside to outside, usually caused by improper toe-in or hard cornering) or along the circumference (hard acceleration and braking or insufficient rotation). Is that a decent generalization?
Originally posted by VelociRacer: You can call it by many names, saw-toothing, feathering, cupping... It happens on any tire that is not rotated properly or frequently enough.
quote:I've given up on symmetrical tread design, especially the V-pattern, because they they all turned out to aggravate tramlining to the point oif being noticeable or even or annoying. In theory, a wedge-shaped grooves should help evacuate water from under the tire better than other patterns. On a dry road surface, no tread shape or even having a tread pattern makes sense (other than in regard to noise). The road's surface texture (or lack thereof!) is what provides "bite." A slick (not any bald tire, Jethro!) is stickiest on dry.
Does the V-shaped design have any merit?
quote:The point I want to make is that there isn't enough water on Tire Rack's test track and it is much closer measuring dry traction than I think it ought to be. Put another way, you can sense and measure the affect of hydroplaning resistance has on tire traction at much lower speeds and much lower water depths than one might think.
Originally posted by wantin150: If I'm not mistaken, Tire Rack tests the wet traction of a tire but not the hydroplane resistance of a tire......
quote:I recall a "Gatorback" tread design that was earlier, based on F1 race tires. "Gaterback" was not the name of the tire, but a popular name because the design looked that way. What was "unique" was that the Aguatred used a channel in the middle of the tread. This was actually an outgrowth of a "twin tire" idea someone had. Others had used the channel concept before, but Goodyear popularized it.
Originally posted by outrun: ....Side note? Was GY's Aquatred I the "pioneer" of directional treads for street applications?....