Tire cracks

[Guest]

My old GS1100 developed some sidewalk cracks over the winter when the air valve leaked.

When inflated, all looks normal however by buds tell me it's unsafe.

Anyone heard of a tire blowing up from side wall cracks ?

[tkent02]

We need the date code, which tire is it and we need pictures of the cracks.

[Remington44-77]

Sidewall cracking with a low tire is a sign of the early stages of dry rot. If your riding is at residential speeds and short, this tire could last quite some time. Be ware, extended rides at Hi-way speeds is asking for it. Start shopping for new rubber.

[Bookmon]

Uh, yea! Blowing from any weak point.

[bonanzadave]

Avon Road Rider ???

[mrbill5491]

Side wall cracks, age, ozone, heat, weather. All bad. Time for new skins period.

[themess]

There was a similar thread a week or two ago.

Short answer: if the sidewall cracked while the tire was uninflated or severely underinflated, and the sidewall cords are still OK, you're probably fine.

The main function of sidewall rubber is to protect the body ply cords from physical abrasion.

Sidewall and tread rubber compounds have antiozonant and antioxidant additives. Those compounds react with O2 oygen and O3 ozone before those oxygen molecules can react with the rubber, making it brittle and leading to cracking. If sidewall or tread cracks appear in a tire that has always been inflated, the protective additives have been used up. However, rubber cracks very easily when it is stretched, regardless of the presence of O2 or O3. Underinflation stretches rubber at the surface, and can cause cracking without oxidation of the rubber molecules.

Your best option is a new tire. But it isn't an emergency.

[1_v8_merc]

Avon Road Rider ???

Haha ouch!

Hey wait a sec...I'm riding on RR's...no problems yet.

[gshub]

I know quit a few people who use RR on their GS/Gsxs and race on them over here in UK never heard of this problem over here (yet).....
I wont use anything else having tried them..........

[argonsagas]

My old GS1100 developed some sidewalk cracks over the winter when the air valve leaked.

When inflated, all looks normal however by buds tell me it's unsafe.

Anyone heard of a tire blowing up from side wall cracks ?

Have not seen any photos nor a date code yet, so I presume none are coming.

A point not mentioned is that cracks are not the size you see, but larger. Always.

While the tire is flat and compressed the cracks begin and grow, but weakness invariably extends beyond both ends of the visible length.

There is nothing else to go with, so I will follow others and recommend a replacement tire.

Never forget: the two most important safety items on your bike are black and round. Everything else depends entirely on them.

[ndaugbjerg]

I agree with everyones comments. One additional thought: Even if the tire seems structurally sound , the tread starts drying and hardening. Now that once sticky road grabber has the traction of a bowling ball.
Niels

[themess]

I agree with everyones comments. One additional thought: Even if the tire seems structurally sound , the tread starts drying and hardening. Now that once sticky road grabber has the traction of a bowling ball.
Niels

No, the tread doesn't really start "drying and hardening", at least not for street tires. Nothing in the rubber dries out.

What can happen is atmospheric oxygen reacting with rubber molecules, and sulfur cross-link density can gradually increase. Tread and sidewall compounds include lots of chemicals that react with atmospheric oxygen before the oxygen can react with rubber. Those chemicals eventually are used up. It takes at least several years of exposure to sun light for this to happen. Properly stored, ten years or more.

As far as sulfur cross-linking, that happens mostly when too much free sulfur is used as the primary vulcanizing agent. The mixture of compounds used to vulcanize rubber used in tires is designed to minimize the increase in cross-link density with age. Again, at least ten years is OK for a properly stored tire.

If the tire is getting cracks or getting hard while sitting there, it is time to replace it. If the rubber still seems soft and there are no cracks, there is no reason to worry. Rubber technologists use the Shore Durometer to quickly test rubber hardness. Owners can do OK by using their fingernails, and comparing it to a nearly new tire of the same make and model.

[ndaugbjerg]

The tires on my 450 looked almost new when I bought it. Closer inspection revealed a lot of sidewall cracks and the tread area was hard as a rock and slick as owl poop. I cut them up before trashing them so some poor guy would not be tempted to use them. A fter 50 years of riding I still don't know much about free sulphur or cross-linking but I know when it's time to put new skins on the beast.
Niels

[gsinister]

I have to agree it's time to replace them. But it still reminds me of the scene in The World's Fastest Indian when Burt rubs shoe polish into the cracks of his tires to pass inspection on the Salt Flats. Good movie.

[themess]

The tires on my 450 looked almost new when I bought it. Closer inspection revealed a lot of sidewall cracks and the tread area was hard as a rock and slick as owl poop. I cut them up before trashing them so some poor guy would not be tempted to use them. A fter 50 years of riding I still don't know much about free sulphur or cross-linking but I know when it's time to put new skins on the beast.
Niels

Firestone started really destroying factory scrap tires in the 1970s to prevent re-use. At first, they just cut the beads, but some idiots welded the wire back together. I think that Firestone then cut both bead completely out. Tire disposal is difficult.

I learned about rubber chemistry and technology by taking correspondence courses and working with it in factories. It is really, really boring unless your income depends on it. Then it is merely boring.