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

Retro Grouch 

I've seen sidewall markings like that. The ones that I've seen I assumed were caused by riding at low air pressures.

madpogue 

Are you in a rural area? Are there unexplained reports of crop circles matching your tire tread?

Okay, sorry. I wonder if this in part is the rubber drying out in the low humidity. Or maybe salt is eating away at the sidewall rubber. Or maybe some of both. Not sure what to do about it; is there some kind of conditioner/restorer for tire rubber out there? Perhaps even something like ArmorAll will help.

dafydd

I tend to agree with retrogrouch, although high pressure could possible do the same thing. It's also something I generally see happening only to skinwalls. I've been told Armorall pulls oils out of tires, but it may be worth a shot, they're not getting any better on their own...

TonyD

Thanks for the info. I'll double check my pressure and give the armor all a try. Will also be ordering another set of tires...

Tony

trailhound

I get the same type of marks on my tires.... I also think it's from low air pressure, since I run mine a little low.

Put the Armor All down and step away from the bike!!!!! Before you use that stuff, PLEASE remove the tire from the rim! Don't get any on the braking surface or the tread! If you thought ice was slippery.... !

Peace

Avalanche325

Those are normal sidewall wear marks.
Please please please, do NOT put Armor All on a bicycle tire. Unless you feel a need to impact test your helmet.

I know a guy who wrecked a Kawasaki Ninja 600 with less than 5 miles on it. The dealer put Armor All on the tires because it looked pretty in the showroom. On the first turn the rear just shot out from under him. He got a brand new bike out of the deal.

TonyD

Well, that's a bummer. I just sat down to read the forum after washing the armor all off my hands from putting it on my tires..... Thankfully I didn't put any on the tread, just did the sidewalls.

I also think I may have been running the pressure too low, my rear was about 20 so I filled it to about 55.

Guess I'll go degrease my rims....

Tony