This is an excellent conversation! As I mentioned, I've noticed this a while ago, but haven't been too concerned. I'm lazy and cheap, ya' know. The split runs completely round the tire on one side, and is barely visible as a hairline forming on the other side. The front tire is in better shape, but I can see the beginning of a hairline forming on one side. As noted, high and dry temps down here in inland SoCal. That must prematurely age the sidewalls significantly as these are maybe three years old at the most (Nashbar's blow out sale when they were selling them for $16). I guess this is the downside of living in the desert. Bill, do you have any problems in AZ? The threads are in fine condition, but very exposed. I'm inclined to keep running them, but being on the look out problems. The rear tread is pretty worn with all the "slits" being worn down to totally smooth in the center. Brake pads are centered properly.
If you look at the real big full-sized photo, you can just almost make out the threads in the casing if you squint sideways: http://www.flickr.com/photos/cyclotourist/4103817724/sizes/o/ Fun with bike parts! On Sat, Nov 14, 2009 at 4:40 PM, Bill Gibson <[email protected]> wrote: > My criteria for tire replacement is whether the carcass fabric is > compromised or not; no bulges or cuts in the sidewall. Cork life will reglue > the stray fabric edges, and seal exposed threads, but I hope to wear out the > tread first, which is always a satisfying proof of much riding. Confidence > in tires is important. > > > On Sat, Nov 14, 2009 at 4:58 PM, EricP <[email protected]> wrote: > >> >> The last set of tan sidewall Pasela tires did the same thing. Like >> Angus said, it seems to be where the glue line is. My opinion was the >> glue was too strong and not letting the rest of the sidewall flex. >> This set also had about 2,500 to 3,000 miles on them. So it was time >> to change anyway. >> >> My own tires were/are 700x35 and run at about 60 pounds (front) and 70 >> to 80 (rear). May still be underinflation for my weight at the >> time. >> >> Still have a pair of blackwall Pasela tires that sit in reserve. If >> the present Schwalbe Marathon Supreme tires get tiresome then will try >> them. >> >> However, have to admit that since going to 40mm wide tires, even 35 >> seem pretty skinny. >> >> Eric Platt >> St. Paul, MN >> >> On Nov 14, 5:18�pm, R Gonet <[email protected]> wrote: >> > Nice analysis, Jim. �It would be interesting to ride the tires until >> > they fray to see how long they would go, but I tend to replace tires >> > on my cars and bikes before I need to. �I think the newer tires are >> > safer, it gives me peace of mind, and it's a small luxury that I can >> > indulge in. �Kind of like buying new sneakers before your old ones are >> > worn out. �This also offsets other riskier, even dumber, behaviors >> > that I engage in. >> > >> > Thanks for the post. >> > >> > Richard >> > >> > On Nov 14, 4:57�pm, CycloFiend <[email protected]> wrote: >> > >> > >> > >> > > on 11/14/09 12:50 PM, R Gonet at [email protected] wrote: >> > >> > > > I just checked my 2-year-old Jack Browns and they have that same >> split >> > > > all the way around, though not as bad looking as the much older >> Pasela >> > > > tan wall. �The split appears to be in the outer gum wall, if that's >> > > > the correct term, and doesn't look like it's penetrated into the >> woven >> > > > layers below. �I don't know if this is a safety issue or not. �I've >> > > > never heard of a tire failing at that point before, but confess to >> > > > little knowledge on the subject. >> > >> > > > By the way, it's very easy to check your tires without removing >> them. >> > > > Just deflate them all the way and push the tire bead away from the >> > > > rim, working your way around the tire to inspect the circumference >> > > > visually. >> > >> > > > Is there anybody out there who has some knowledge in this area who >> has >> > > > an opinion on the safety issue? >> > >> > > Hey. It's the internet. �I'll hazard a guess... >> > >> > > If you work from the outside in, the tire layers consist of "contact" >> > > material (the black part of a skinwall), The underlayer (the >> skinwall), the >> > > thread/casing, and a thinner layer. >> > >> > > AASHTA -http://www.sheldonbrown.com/tires.html >> > >> > > In the photo that David E shared - >> http://www.flickr.com/photos/cyclotourist/4103817724/ >> > >> > > I notice two things - first, the cracking parrallel to the rim, second >> the >> > > whitish "fold marks" from running at relatively low inflation. >> �Overall, the >> > > sidewall looks pretty dried out - certainly drier than my tires. >> > >> > > David rides in an area which has consistently high ambient temps, >> which I've >> > > always found to degrade tires quickly. My experience is that the >> > > skinwalls/sidewalls go first. >> > >> > > If those were my tires (and lemme just say that I may have a higher >> > > tolerance for risk than others here, and if you base your actions on >> my >> > > opinions, I can't take liability for it....) I'd run 'em until I start >> to >> > > see the beginning hints of threads fraying through. But, I'm also just >> odd >> > > enough to want to see how they begin to fail. >> > >> > > If the whole sidewall is cracking, I'd replace the tire. �This is how >> you >> > > often find old tires on garage sale bikes - unused tread but brittle, >> almost >> > > "varnished" looking sidewalls. But, if the sidewall is still >> relatively >> > > supple and elastic, I'd run them for a while yet. >> > >> > > IF I could see through to black tube anywhere when they are inflated, >> I'd >> > > pull 'em, cut the bead with a tin snip and not use them. >> > >> > > Back to the photo - >> > > The threads still have to fail, and the thread casing/underlayer in >> general >> > > is probably a bit thicker than the skinwall. �The threads are probably >> more >> > > resistant to heat damage than the surrounding rubber composite. >> > >> > > I think what may be happening is the combination of running larger >> volume >> > > tires at low pressures, while the sidewall itself is drying out a bit >> > > quicker than average. That big footprint of the tire tends to stay >> stuck, >> > > while you and the bike can move quite a bit side-to-side. I would tend >> to >> > > think that's why you are seeing cracking like that. >> > >> > > Just one other semi-unrelated data point - >> > > Riding with a canti brake pad out of alignment, I cooked through a >> brand new >> > > WTB Velociraptor rear tire in under an hour, and the first half was >> > > climbing. There's not a lot of material there. �You might check to >> make sure >> > > the edge of the pad isn't off the edge of the rim, though David's >> doesn't >> > > appear to have done so. >> > >> > > One more thought - >> > > If the underlayer is really dried out, there is a possibility of the >> black >> > > layer delaminating. �(Kinda like a retread auto tire failure). �I've >> > > experienced this with a Specialized road tire (can't remember the name >> - >> > > back in the later 90's) that used a dual durometer compound. But, even >> that >> > > was happening slowly enough that I noticed it between rides. >> > >> > > Hope that helps. >> > >> > > - Jim "who just took his Pasela 32's outside and looke at them under >> strong >> > > light and cleaned glasses..." >> > >> > > -- >> > > Jim Edgar >> > > [email protected] >> > >> > > "One Cog - Zero Excuses" L/S T-shirt - Now availablehttp:// >> www.cyclofiend.com/stuff >> > >> > > Cyclofiend Bicycle Photo Galleries -http://www.cyclofiend.com >> > > Current Classics - Cross Bikes >> > > Singlespeed - Working Bikes >> > >> > > Send In Your Photos! - Here's how: >> http://www.cyclofiend.com/guidelines- Hide quoted text - >> > >> > - Show quoted text - >> >> > > > -- > Bill Gibson > Tempe, Arizona, USA > > > > > -- Cheers, David Redlands, CA "Bicycling is a big part of the future. It has to be. 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