auchencrow

Recently I noticed a little unevenness in the ride on my Nishiki, and saw that my rear tire had developed what I call a "wow" or a "warp", such that the tread was no longer centered, and the sidewall darn near rubbed the chainstay.

- Yet there was no localized bulge in the side wall at all, no obvious tread separation, and it was a relatively new tire when I bought the bike 2 years ago.

However - When I replaced the tire, I saw this:



What caused this? Is there a way to prevent it?

FBinNY 

The cords broke down and eventually gave out. Causes include both over and under inflation, and possibly heavy use on rough roads. I don't understand what you mean by relatively new when you bought it 2 years ago. If you bought the bike or tire used, there's no telling how old it actually was even if the tread showed little wear. It's a consideration because tires age not only in miles but over time and old tires are more prone to this kind of breakdown.

As for preventing it, the key is to keep your tire properly inflated between 80-100% of the sidewall pressure rating, and to wear it out before 5 years or so.

canopus 

Also once one cord goes, it places more stress on the others around it so that they will fail faster. If you had a puncture in one of those cords in the past sometime then they could eventually lead to that kind failure. Old BMX Snakebelly tires were notorious for it, Firestone car tires were the worst. Haven't seen it to much on quality bicycle tires but pressure is pressure.

auchencrow

Hi FBinNY - You are right to challenge me on that: I would not have believed it myself, except that it's that same tire I use on many flips and several of my own bikes - and those do not exhibit any less discoloration from age, UV or ozone exposure. (The sidewalls tend to turn less yellow in time).

Also, I must admit that I don't know how these tires were inflated by the PO.
They're not super high pressure tires, so maybe over inflation was indeed the cause. I think a lot of people just pump tires past 100 without reading.

auchencrow

Hi canopus - You have cited another real possibility - the prior owner could have traversed across a bed of upholstery tacks for all I know!
... Sort of like the antithesis of "a stitch in time saves nine".

It makes me wonder if its sound to EVER leave tires on a used bike, no matter what the condition.

Doohickie

You got two years out of it, right? That's not too bad.

auchencrow

Hi Doohickie!

"Yeah but" two years sure is not a lot of miles when you have as many bikes as I do!

DannoXYZ 

Could have also come from riding on the tyre when it was flat. The sharp rim-edge can damage the casing in a straight-line like that if you have your weight on it for any length of time.

10 Wheels

I have had two different tires do that at about 1600 miles.
I think they were just defective tires.

Doohickie

I know... same here. But still, you got to put off a tire purchase for 2 years.

blamp28

I had the same thing happen to two lower end Michlin tires in one season. They were defective it turns out. That can happen from time in storage as well as miles on the bike.