Tires that have radial dimples

[Montana_1985]

Can anyone explain/comment on why tires have/get those radial dimples in them??
Our 3650RK has these on all four tires..and i just noticed that my new Goodrich tires on my F350 is showing this pattern as well..

1) Is this normal?
2) Is this a dangerous situation?
3) What causes this?

I've seen plenty of tires do this, and this is why I got new tires on my F350 as the old ones were not only worn out, but all had these sidewall dimples in them...

This is not a bulge, per se, but rather a concave radial dimple from rim to tread..
Any ideas folks?

[Glenn and Lorraine]

1- YES
2- NOT AT ALL
3- Not realy sure but it is a common thing in nearly 100% of radial tires. The term my brother, who has 30 years in the tire business, used was "polyester bunching". Has something to do with the heating and chilling of the polyester during the manufacturing process.

[NJ Hillbilly]

I have very obvious ones on some Goodyear trailer tires. The tire dealer called them "undulations" and they are completely harmless.

John

[Glenn and Lorraine]

Yeah that word...."undulations"

That was one of the words my brother used to describe the dimples

[sreigle]

Yes, but you have to be careful because a broken belt often looks like a dimple, just usually deeper than the surface blemishes. We've had that on two Goodyear Marathons on our Montanas and the Goodyear dealer proclaimed them defective. The first one was replaced free, the second pro-rated.

Here's the reverse of a dimple, also a defective Goodyear Marathon (the bubble got worse than this before the new tire came in).

[Montana_1985]

I've had a trailer tire do just the above picture...
THanks for the replies!! I've just never seen so many tires doing this..in the 70's and 80's, i've NEVER seen a tire do this..just in the past 10 years or so...
I'll keep an eye on those "undulations" though....

[Glenn and Lorraine]

It's a radial tire thing and is very common.
Steve, your's is called "seperation". The rubber sidewall has seperated from the boby plies.

[sreigle]

Glenn, that tire sat in the bed of my truck for almost a week before the new tire finally came in. I was just waiting for that separation to become a divorce!