Um, what causes this?

It's called a recap. Their used tires that have been retreaded with the old sidewall. Tread is more or less glued on. Recaps are for saving money, not equipment or lives.

If you look real close to the inside tire, you see that line that runs across the tire? That's where the wrap meets back around, and is always one sure way to tell if there recaps. Also, alot of times, you can tell by looking at the sidewall, almost to the tread, a lump all the way around the tire.

 

Exactly right, but at least you have/had tread. More than you had from elsewhere eh?
What did they do? It looks your mudflap is on backwards.

 

You had what I call a Zipper failure. Someone where they recapped that tired SCREWED the pooch and forgot to xray it to check for bubbles inbetween the tire carcass and thread cap. Got hot and what you see is what happens. Could have been alot worse could have hit the car next to you or ripped your airlines out or taken out your fuel tank.

 

That was good luck. It came off pretty darn clean by the looks of it. If part of the adhesive holds the end of the cap you can take out mud flaps and brackets, cross members or lights and bumpers. Imagine how much force a 1"x11"x8ft hunk of rubber generates at 65 mph!

Why it came off can be a mystery, but as a rule the biggest enemies of caps are heat and abrasion. Heat deteriorates the adhesive, abrasion breaks the seal of the cap to the tire mechanically. Think of what would separate the sole of a sneaker from the leather foot of the shoe and you have it. Low air pressure creates heat and flexes the tire. Heat and abrasion in one easy step.

 

hey JS

check out any NEW tire and you will see the same seam, just hidden a bit better

new or caps....the tread is installed the same

but iroc.....the cappers screwed up and didnt get it on all the way right
all tires suffer and degrade with heat and over/under psi

 

a new old re cap is the worst as they haven't cured property , re-caps need to mounted and ran like heck as soon as possible after getting caped to help the curing process

 

Good eye johnday, looks like a mechanic, or a driver on the road, was in a hurry to replace the mudflap. IROC, you were lucky the cap didn't take out your trl. wiring also. Be Safe out there.

 

Its odd that it only blew the center part of the tread and not the sides also. Usually a cap take all the tread off.

 

Aw, you just gave birth to an alligator!
Go smoke a cigar!