Losing your spare tire is synonymous with losing weight, for people and now for cars, but will car buyers give up their spare tire in exchange for higher fuel economy and lower operating costs? Automakers around the world are weighing that question.
Customer and regulatory demands for higher fuel economy led to the creation of the compact temporary spare tire in the 1980s. The same pressures now may eliminate the spare tire entirely.
“The general rule of thumb is that a 10% reduction in (vehicle weight) leads to a 6-7% improvement in fuel economy,” said Jay Baron, president and CEO of the Center for Automotive Research in Ann Arbor.
Automakers are replacing spare tires with tire sealants and an inflation kit to fix most flats. The tire sealant and inflation kit weigh 5-6 pounds, compared with 30 or more for a temporary spare and 50 or more for a full-size spare and its tools, GM director of chassis engineering Terry Connolly said.
“Engineers sweat bullets to reduce a car’s weight by grams, and this is a way to shed 40 or 50 pounds,” said Bill Visnic, Edmunds.com senior editor and analyst. “Not every customer is comfortable with it, though.”
Although tire reliability has increased, drivers still fear being stranded. That’s become less likely because of the widespread use of cell phones. Tire-pressure monitors on all new vehicles also make drivers aware of most leaks before the vehicle becomes disabled.
A survey by General Motors found the average driver gets one flat tire every 30,000 to 40,000 miles. In two-thirds of those flats, the air leaked out while the car was parked in the owner’s driveway. About one-third of respondents to a study by tire maker Michelin hadn’t had a flat in the last 10 years.
Despite that, AAA Michigan makes 130,000 road service runs for flat tires every year, and there’s always the possibility of a blowout the fix-it kit can’t repair.
With help easily available through cell phones, many people choose not to change flat tires even if they have a spare.
The benefits from eliminating the spare are too big for most automakers to ignore, though. A 1 m.p.g. difference in the fuel efficiency of a compact car such as the Chevrolet Cruze or Ford Focus will save the driver $50-$100 annually at the pump at current prices, according to the Department of Energy.
Most automakers figure full-size spares still are mandatory for pickups and SUVs that will be driven off-road. For most other vehicles, including smaller crossover SUVs, the trend is to provide repair kits.
Many drivers probably would be surprised to find out they already have a repair kit rather than a spare, said John Rastetter, director of tire information services at online tire retailer the Tire Rack.
“For most flats, a can of sealant and an air compressor does a great job,” he said. “Despite that, we hear from some customers who like the spare tire as a security blanket.”
For that reason, some automakers sell an optional spare tire for vehicles that come without one.
“It’s a question of trade-offs,” Visnic said. “Carrying a spare tire you never use 100,000 miles burns a lot of gasoline. It’s like driving around carrying a fully packed suitcase with a week’s clothes, just in case you have to go to the airport and don’t have time to pack. How often does that happen?”