Contour Enthusiasts Group Archives Forums General Troubleshooting Bulge in tyre sidewall.

I'm no expert by any means, but I think you should put on the spare and replace the f'd up tire ASAP. I'm fairly certain that sidewall damage of any kind can't be repaired and this bulge is definitely a critical weak spot that is going to fail disastrously one of these days. The usual cause is an open splice in a body ply. Where there should be some overlap between the plies, there isn't any where you see the bulge. Though it may not look cool to roll around on the donut, you might save yourself from having to replace your 17" wheel when the tire does finally blow. With such expensive tires, you may want to look to see if there is a warranty against defects like this. However, it may be tough to prove this wasn't the result of hitting a pothole or some such thing.