DETROIT -- The 2020 Ford Explorer will offer tires that patch their own holes. Drivers may not even know they ran over a nail, but here's what they should know:
The tires allow them to keep traveling after a puncture, in some cases continuing for days without a repair. They use different technology than run-flat tires, which have been criticized for rough rides.
Most drivers won't even know they had a puncture until they notice a nail stuck in the tire or tire-pressure warnings alert them to a gradual loss of air pressure days after the puncture, according to Michelin engineers.
The concept of self-sealing tires has been around for years, but recent improvements -- and automakers' eagerness to save weight by eliminating conventional spares -- means we're going to see more of them.
"Self-sealing tires are designed to handle the most common tire puncture -- a small object penetrating the tire in the tread area," said Woody Rogers, director of tire information for online retailer the Tire Rack.
Michelin makes the Explorer's self-sealing tires. It also supplies them to the Chevrolet Bolt. Most major tiremakers have tires with the technology, and the number of choices is only likely to grow.
The inside of the tires is coated with viscous goop that flows into punctures to seal them.
"When the sealant works as designed, most drivers never know it's working. There is no pressure loss, and odds are the driver doesn't see the object in the tire or it's fallen out," Rogers said.
Creating the rubbery sealant was tricky, Michelin engineers said. It must flow into punctures, but it can't pool at the bottom of the tire when it's parked. The material also must form an airtight seal, and flow at temperatures from scorching desert blacktop to a frigid winter night.
Unlike run-flat tires, which have stiff sides that allow them to keep rolling after the air leaks out, self-sealing tires can keep going for days after a nail or similar object punctures them.