So halfway through today's ride, my rear tire (a Continental Contact) picked up a roofing nail.
Weird puncture: The nail entered and exited the sidewall. Looked like something skewering the cheek of a facial-hardware enthusiast. Had to push it out with a tire lever.
it didn't pierce the tube. But I don't carry a spare tire, so I immediately rode home (which is why it happened halfway through the ride). Made it back fine, so maybe I weenied out. Now I'm wondering what to do with the tire. It's hard to even see where the nail was. But maybe the sidewall's integrity is shot.
Would you:
— Dump the tire. It's unsafe at any speed.
— Use it for a spare.
— Keep riding on it. It's probably just a cosmetic issue.

The sidewall is compromised. Dump it. It is not worth taking a chance of you getting hurt or worse.

Next time carry a tire boot. A piece of leather or thick cloth. Paper money (dollar, euro etc) will do in a pinch.

If you cant see the hole (ie not a big gash), I would duck tape the inside and ride it.

I'd probably ride on it, but that doesn't mean it is the best thing to do.

I'm a cheapo.. If it's not to large I would just take a small piece of old tire and glue it to the inside of the hole.

I repaired a tire like that once. I just put some fiberglass filament tape on the inside, it held for years, eventually sold the bike.

Wow that's weird. Yesterday I had the same thing happen, to the same tire.

I'm replacing it right now.

If you should decide to boot it and continue riding it, keep it on the rear. Never put a questionable tire on the front.

replace the tire better safe than sorry I say.

In a sidewall, there isn't a lot of there there to hold everything together. If the nail went through the sidewall twice, that's an awful lot of damage in a relatively small area. If the nail sliced any of the sidewall threads (and you would see the end of the thread around the hole it did), replace the tire without question. Even if you decide to keep it, boot it and watch it closely, and if the holes get any bigger, replace the tire.

If your finances let ya, replace it, if not, then if the tire's big (conti contacts come in a variety of sizes) maybe get by with a repair for a bit, but definitely on the back. I had a sidewall collapse in a turn once, slid sideways, caught a fence & woke up on the trail needing a new helmet, & front wheel, no fun at all.

I would glue a bit of an old tube or tire to the insides of the holes. Barge works pretty well. But as staehpj said, it may not be the right thing to do.

I'd replace that tire. Wouldn't want to have to worry about it blowing out. Even tho with a boot, the odds of that are extremely small, and if on the rear, probably survivable. Still, not worth the nagging concern about its integrity.