TonyD

Hello, have a question that is puzzling me and I hope someone can
help.

I have a 99 Specialized StumpJumper Comp. I commute to work in
Michigan, about 2.75 miles each way. It is cold out but the sidewalks
are usually clear, maybe ride a little ice and packed snow at
intersections.

My question is my rear tires are getting these weird diagonal lines on
the sidewalls where the tire just seems to be thinning out. This
first happened on a Hutchinson Alligator. I only noticed it when a
few of these wearing out bands got so bad that the tube was actually
bulging out. So, I switched it out for a Specialized Dirt Master comp
which is on a different rim. Now I am noticing the same wear pattern
on this second tire.

It is multiple diagonal lines that run almost the entire width of the sidewall. It is happening all around the tire and on both sides. They are spaced less than an inch apart and it just looks like it is wearing or thinning out in these spots. I thought at first it must be rubbing but I can't see anywhere that the tire doesn't clear the frame and the brake pads aren't far enough out to cause it. Also, I can't hear any rubbing when I ride. It is not abrasion from rocks or
whatever because I am riding only on the sidewalks and roads, and only
very occasionaly these aren't cleared of snow. Is it the cold? It has been down around zero for a month or two and I store it outside during the day (covered), and in the basement at night. Haven't had any problems with the front tire though, still has the Hutchinson on it and no problems. Is it just wearing out from old age? Again, the front tire still looks great.

Any Ideas?

Thanks,
Tony