Then, after driving around for 15 minutes trying to locate the tire shop a customer had told me about and not finding it, the light went out. I figured maybe it was just low pressure because the temperature was about 40 degrees and it was raining; sometimes those warning lights come on under those conditions.
The trip home was uneventful. Sunday morning it was obvious the tire was low, but repair would have to wait until Monday morning. But, by Sunday evening the tire was completely flat so I had to put on the spare.
Monday morning I drove to the tire shop and they couldn't find any leaks so they just pumped it back up. This was done at no charge.
It was very low again Tuesday morning, so it was back to the tire shop. This time they found a nail in the tread, but it didn't penetrate, so that wasn't the problem. But they finally found a shard of metal that had penetrated the tire's shoulder at an angle making it unrepairable, so I had to buy a new tire...cost: $221.
Since the introduction and use of the radial tire the recommendation for sidewall repair has been if a tire's sidewall is ripped, it's best to throw the tire away and purchase a new one. It is expensive, but with the way radial tires are made and anchored, if you rip through the radial that underlays the tread with a sidewall tear, you are just putting yourself at risk.
There is really no good way to repair a puncture in a sidewall unless the tear does not penetrate the radial ply itself. In addition to objects on the road such as nails, sidewalls can get punctured by hitting a curb, small accidents, and bent rims.
Unfortunately, sidewall punctures can’t be repaired because the patch won’t hold. Tires have cords that run all around the tread of the tire, the part the makes contact with the road. But on the sidewall, those cords aren’t there. So, there’s just no way for a plug to fill the hole.
Obviously, if the patch won’t hold, it’s going to continue to leak. Also, sidewall puncture repairs compromise the integrity of your tire. Even if a patch were placed over a sidewall puncture, the fact is, your tire is no longer able to perform at is best and that means it isn’t safe. Even at slow speeds it will be is susceptible to a blowout and the risk of serious injuries for everyone in your vehicle and those around you. When you have a sidewall puncture the best thing to do is replace the tire.