2017 Chevrolet Bolt: Headline Self-Sealing Tire Saga
by Mike Schmidt, Senior Manager, Vehicle Testing Operations
It started with a tire pressure monitoring system (TPMS) warning Saturday night.
The left rear tire on our 2017 Chevrolet Bolt was down to 23 psi from 38. A quick inspection showed no obvious visual, or audible, cues of puncture. So we aired it up to 45 psi and parked the Bolt for the night. By morning it was back down to 41. While there was some relief that it was a slow leak, we still had a problem. Our adventure began the next morning at the tire shop.
The shop was busy when we arrived, but we just needed a patch and figured that it wouldn't take too long. The tech got the tire off and easily located a run-of-the-mill perforation in the center of the tread. Inside, we discussed our options with the rep behind the counter. "That is a special tire," she began. "It has a liner inside that is there to self-seal holes, so we can't patch it. We don't carry that tire in stock. I'll need to order one. It will cost ..." At that point we tuned out.
This explanation was frustrating. It seemed unrealistic that the tire could not be repaired. But since it was still holding air, we had some freedom to explore other options. We thanked the rep politely, asked that the tire be put back on the car, and left.
That evening at home, we decided to take a gamble and drive the Bolt to the office. Another car was waiting there for us to switch into and we could deal with the tire on better terms Monday morning. At the rate of this leak, the odds were in our favor. And logic convinced us that, if we left now, we'd still make it home in time for Game of Thrones.
As we reached freeway speeds our predictable, slow leak opened wide and the tire pressure fell quickly to single digits. We safely exited and parked at a gas station. Inside we purchased a can of Fix-a-Flat, still set on the idea of limping the car back to the office.
In short time the sealing foam was everywhere. It oozed from the puncture hole in the tread. It oozed from the valve stem. Despite the signs suggesting it was futile, we tried airing the tire up. It hissed back at us angrily.
"Hello, OnStar? We need a tow." A truck arrived about 15 minutes later and transported the Bolt to the nearest Chevrolet dealership. While waiting for the truck we called home, "This isn't over yet. Will you pause Jon and Daenerys until we get there?"
The next morning about 7:30 the phone rang. It was Martin Chevrolet: "We have your car. We'll take a look at the tire when our techs arrive and call you back. Do you prefer text or phone call communications?" At my request, a text came through at 10 a.m.: "We were able to patch the tire. Your car is ready for pick up. It will be $35."
This was much different than our first tire shop experience. So we called a third outlet. This tire shop told us it hadn't seen any Bolts yet. But in dealing with self-sealing tires over the years, they typically removed the tire, manipulated the sealant from inside until it covered the hole, and then put the tire back on. With such varying approaches, we contacted Michelin directly for clarification.
Michelin Selfseal technology was specifically developed for the Bolt. According to the website, it works "by sealing most punctures up to one-quarter inch (in length)." The site doesn't explain how to repair them, so we reached out to Brian Remsberg at Michelin public relations. He was a big help, sending us the inspection and repair procedure bulletin. The quick version was that the patch install is just like a standard tire. The long version follows, step by step:
1. Identify the puncture inside the tire.
2. Bore the hole from the inside following its trajectory.
3. Spread the adhesive directly without brushing. Let it dry for 5 minutes.
4. Remove the protection without touching the uncovered surface.
5. Insert the stem from the inside.
6. Pull the stem smoothly from the outside.
7. Roll over the stem head, moving from its center toward its edge.
8. Cut the protruding part on the outside without pulling the body of the stem.
The conclusion is that Martin Chevrolet did it the right way. And both of the tires shops we consulted lacked the information to repair the tire properly. It seems appropriate to mention that neither was a Michelin-branded shop. Should that matter? But the story didn't end here.
Less than a week later, the same tire had a slow leak again. This time we got it to our garage with less drama. Fearing the worst, we called for tire availability before even taking it to the shop.
Nobody had one in stock. We tried Tire Rack. Tire shop No. 1 couldn't source the tire at all, but it could get the non-self-sealing version. Dealership No. 1 needed two to three days. Dealership No. 2 said it could "probably" have the tire the next day. Dealership No. 3, the largest in our area, could "get it next day if we ordered it early enough." Tire estimates varied slightly but averaged about $150. We sent a note into the tweetosphere, "Hey @MichelinUSA. Need to replace a @chevrolet Bolt tire. Tire is completely deflated. No local supply. No Tire Rack. Need one. Advice?"
Michelin was quick to respond, saying it had just shipped us a tire. We should see it the next day. This wasn't the channel we wanted to use, but we were grateful. And having the tire in hand gave us some flexibility to perform other tests on the damaged tire. Because at this time we didn't know the cause of the leak yet. Another hole? A leaking patch? The tire arrived as anticipated and we headed to our local shop, Stokes Tire.
Stokes removed the tire to find an anti-climactic second puncture. This hole was in the shoulder of the tire and could not be patched. So we took a lot of photos and replaced the tire. We kept the old one for posterity and internal education. After our first, and second taste of self-patching tire technology, we're not sold. We paid $30 to the shop for labor and hit the road.
Mike Schmidt, senior manager, vehicle testing operations, @ 8,503 miles