Continental’s GP4000 S II are extremely popular among road bikers, but they have a reputation for getting cuts in their sidewalls. Whether this reputation is deserved is unclear… any lightweight racing tire is trading weight and casing durability for speed, so the failures shouldn’t be entirely surprising.

After the sidewall is cut, replacing the inner tube will just lead to another flat. The tube bludges out through the cut and gets nicked by road debris. It’s critical to be able to repair a sidewall cut on the road, just to get home. To that end most cyclists carry tire boots or use a dollar bill to bridge the tire gash for the rest of their ride.

I’ve had a sidewall fail badly enough that a dollar bill wasn’t sufficient and the tire blew out a second time on my ride home. That left me wondering if the sidewall gash could be stitched, instead of just bridged by a boot.

So here’s a badly cut sidewall sewn up with dental floss and a normal sewing needle. Sewn sidewall cut

And here again after 20 miles of riding, looking about the same: Sewn sidewall cut

After the 20 mile test I threw the tire away… the risk isn’t worth saving a few dollars. But as a way to get home after a sidewall cut I think sewing the gash closed is a solid choice. Combining the sewing with a tire boot or dollar bill would offer double protection against a second blowout.