cyclezealot

Should I just throw it out. The newly installed tire is a Michelin Krylion road tire. It can't have more than 500 miles on it.
What is going on, is about the sidewall, the once solid, smooth black tire , no longer has a smooth rubbery appearance, but, is now a rough surface with a reddish hue.
It's appearance sort of looks like upraised threads protruding from the tire's surface.
Upon installing the new tire the interior and exterior of the sidewall was smooth. Should the tire be trashed.
thanks

MudPie

Are the tires old, age-wise? When were they purchased? Your description sounds the material is “aged”. Can you post a pic? I used to use Krylions years ago and they were a quality tire.

cyclezealot

MudPie. Probably two years ago. I usually keep a few on hand, since I have five bikes. I will post a pic. Should they be old, does that make them unsafe.?
Never would have suspected such a problem. Probably not pertinent. But, as few miles as I drive my car, not uncommon for my car tires to be approaching five years old.

Andrew R Stewart 

Car tire "rubber" and bike tires have less in common in the design goals then most will assume. Most bike tires are thought to have only a few years of shelf life. Expose them to UV and this reduces IME.

I have a couple pf Michelin Endurance Pros that sat mounted but unsed for a couple of years in a basement. They developed a redish residue that could be rubbed off. I sold that bike recently with a fresh set and tossed the old tires. Andy

Bill Kapaun

Heat
Ozone (electric motors?)
UV (sun light?)

MudPie

I don’t consider 2 years to be a long time for a tire. I usually buy tires in advance so when it comes time to change, I have one handy. I assume you kept them indoors. I can’t comment on the reddish hue, but I’d be surprised if their structural integrity is degraded. Tires are made with layered construction. The strength comes from the underlying layers that aren’t visible. You might want to repost under a more specific title to attract a more targeted audience like “Michelin Krylion with reddish hue - what gives?” Perhaps others have experienced the same.

cyclezealot

Me neither. ^.
I took off the tire. Whatever that outside material was atop the sidewall, the sidewall's exterior was quite easily crumbled. The interior of the sidewall seemed as rigid as ever. Better not to take a risk . Chalk it up to either shoddy production , or it is older than I thought.