| Author | Message | ||
     Gentleman_jon |
It seems that around here, sport riders take great pride on how far they can go on a pair of tires. I must count myself among the guilty. I had mounted a pair of Dunlop Qualifiers in a hurry and didn't take the time to get them balanced. At about 2500 miles of not overly strenuous riding I was down to the wear bars. My long suffering riding buddy, Gerry, had ordered a simple NoMar Classic tire changing machine, but with one thing and another, I had put another 500 miles on the tires before we were ready to change them. At that point they were almost down to the cords, and the bike's handling was getting a bit strange. The guys all said, " Hey you got plenty of rubber left on the sides where you really need it". Long story short, yesterday I mounted a fresh set of Qualy's and balanced them. The difference in handling was stunning. I mean, I expected the handling to improve, but this was a whole new bike. I then realized that with a tread depth of a quarter of an inch, the handling difference between new and bald tires was perhaps the same as 2 to 4 clicks of rear preload. That's a lot. I had added a couple of clicks of rear preload, and took off a line of front preload, to help turn in as the tires wore down. The new settings were even better with the new tires. I guess I will be balancing the tires, and changing at the wear marks from now on. Fitting the new tires made me realize that geometry changes to the bike, and profile changes to the tire due to wear are more extreme than I had believed possible. Your thoughts, brothers? PS. The NoMar Classic tire changer, at $600 is a great idea, especially if a couple of guys chip in. However, changing tires on this little machine is a lot more difficult than it appears on the video. I am sure it will get easier as we get a little practice, but it took us a couple of hours to do it the first time. The guy on the factory video does it in 21 seconds. | ||
| Trojan |
If you ride mainly on straight roads the profile of the tyre will 'square off' pretty quickly and handling will suffer drastically as a result. The thing is, as Jon said, this is such a gradual process that you don't notice the full effect until you change to new tyres again..then Whooaa! Dunlops seem to suffer more from this than some other makes in my experience, and seems to be because they start with a much taller almost triangular profile. I prefer Metzeler or Pirellis. Better still, stick to roads with lots of corners  | ||
| Djkaplan |
"Dunlops seem to suffer more from this than some other makes in my experience..." I noticed that, too. When I replaced the worn out and squared off 207's on my bike with fresh ones, there was a noticeable difference in the way the bike felt, much more so than when I replaced the Metzeler M1's on my bike now. I'm sticking with the Metzelers for the time being. Can't wait to try the M3's. | ||
| Jlnance |
I changed the front D616 on my Uly at 6000 miles. It still had a plenty of tread left, but it was cupped. The difference in handling was astounding. I'm not running the fronts down to the bars anymore. The handling of the bike suffers too much after the front cups. | ||
| Tpoppa |
I think the effect of worn tires is even more noticeable on XB's than other sportbikes with slightly longer wheelbases. My XB is very sensitive to ride height (preload) adjustments. For me, 1 click of rear preload makes a significant difference in steering sensitivity and stability. And just like G_J said...the effect of bald tires is equal to several clicks of preload. | ||
| Nutsnbolt |
Yeah, I am completely unhappy with my Qualifiers. I'm moving over to the Diablo Stradas. Changing of the tyres... Priceless. I do all my own stuff also, including balancing. Beyond that, it's just so much more satisfying knowing that you can do it yourself and aren't reliant upon some other yokal scratchin your rims or overall just running on faith. When you do it yourself, all you have to blame is yourself. Plus you can ensure that you have done all the propers like lining up the valve stem with the dot and going over the balancing a few extra times just to ensure it's right. I hated my 208's. Loved my Qualifiers until I realized just how fast I was running through them. Now, time to go back to old faithful with the Stradas. Just as a sidenote.. I used to have an MZ Skorpion and I used the M1's and (this was my wifes bike) she ran through them like it was funny. Plus, she is the opposite of aggressive but she's also not stupid either. She likes the twisties just as much as the next guy/girl. But, man, I don't know if it was just a bad batch or what but we got about 1000 miles out of them and had to switch. Switched to Pilots and got probably 6000 miles off them. So, I liked the way the M1's handled but hated the wear of them. Enough of the rambling. Sorry. Mark | ||
| M1combat |
The M3's rock Dj. | ||
| Tx05xb12s |
I rode my first two rear Dunlop 208's down to the cords and used the front tire through both rear tires. Then I switched to Diablo Corsa III's and was shocked at how much difference it made in my bike's handling. I didn't realize it at the time, but I was really having to work cutting good lines through curves. I believe the difference lies in superior tires in good condition. I have learned it not's worth it to run around on cupped fronts and bald rears just to save a few bucks. Now I swap out both tires every time the rear hits the wear bars. The bike is much easier to ride and safer to boot. | ||
| Tunes |
If the shoes you wear every day slowly lost their grip to the point you slid every time you walked, you'd change 'em, right? I look at tires the same way. I don't like my bike sliding when I go around corners. When my tires reach the wear bars, like others, I too buy new tires. To quote Tx05xb12s "The bike is much easier to ride and safer to boot." I agree. | ||
| Trojan |
Just to make the water even muddier, it isn't just te wear that you can see that affects grip. Tyres 'go off' after being heated and cooled a number of times, and the amount of heat cycles a tyre can take beofre losing performance is less than you may think. Each time the tyre heats up to operating temperature then cools again is one heat cycle. Each time the tyre gets hot it releases chemicals within the 'semi cured' rubber that make the tyre cure slightly more and get slightly harder. The softer and sportier the tyre to start with the less heat cycles it takes to make the performance drop off. Something like a Metzeler Racetec 'road legal' treaded race tyre will have lost pretty much all of it's grip before you even see the wear bars appear, and are really only good for a weekend's racing if that. Harder touring or sport touring compounds can cope with more heat cycles, but I read somewhere (can't find it again unfortunately) that 70 heat cycles will pretty much finish most tyres before they are physically worn out. Careful 'scrubbing in' of new tyres can increase this a little. One of the reasons for using tyre warmers in racing (apart from the obvious one of warming the tyre before a race) is to keep the temperature relatively constant and cut down on the amount of heat cycles the tyre has to endure. Here is part of an interesting article I found. It talks about car tyres but the technology is exactly the same: Heat Cycles Rubber is a complex substance, a mixture of materials and chemicals manufactured with mechanical processes and various heat and pressure cycles. In use, tread rubber sees mechanical working and time at elevated temperatures very similar to the processes it saw as it was manufactured. It makes sense that more of the same processing would further change the rubber. The material in a new race tire is semi-stable. If the tread rubber had been totally cured it might be too hard to do its job. So stress and heat can continue the curing process. Even small amounts of energy from ultraviolet wavelengths in sunlight, ozone in air, heat, or mechanical working can cause the rubber in a tire to continue its vulcanization process or change in some way. The first heat cycle is called scrubbing and was described earlier. Every heat cycle changes a tire to some degree, generally in the direction of harder, less flexible, and less adhesive. Race tires can loose effectiveness before the tread wears through if they go through many heat cycles. For some tires three cycles is too many, while others show a performance drop off initially and then maintain a good level of performance until the tread is worn off. Smart race organizers are incorporating long-lasting tires into their rules so that "spec" tires can lower the cost of racing. (Message edited by trojan on November 18, 2006) |
