By Edward Noga, Crain News Service

AKRON (Feb. 1, 2012) - - Let's talk about spare tires. And I'm referring to both the one in your car's trunk, and the other that might be around your waist.

There's a connection here. Really.

Everyone knows how much auto makers loathe the spare tire. It takes up space, adds weight to the vehicle, causes lower gas mileage. That's why the full-sized spare mostly is a relic of the past, replaced with those acceptable "donuts" - - tiny spare tires, not sugar-encrusted treats. And the goal of making run-flat tires the norm still has legs.

The tire industry has struggled mightily to get its product to lose weight. At the same time, the behavior of society, at least in the U.S., has been negating that effort.

Here are the facts, something I read in Detroit-based Automotive News, which is published by our parent company, Crain Communications Inc.

The average adult male today is 28.4 pounds heavier than in 1960, and females weigh in at 24.5 pounds more, according to the U.S. Centers for Disease Control and Prevention. That extra weight males are packing is about what a tire weighs on a Ford Mustang, and the additional weight for females equals the spare tire used in a Chrysler minivan.

Put that typical couple and their extra 53 pounds in a car, and theoretically that could cut the vehicle's fuel economy by as much as 1 percent, according to the U.S. Environmental Protection Agency's National Vehicle and Fuel Emissions Laboratory.

Extrapolating that a bit further - - and using a national average gas price of $3.29 per gallon - - the lab said that extra weight added $503 million to national fuel costs last year.

Tire manufacturers and their suppliers spend an enormous amount of money and effort to shave tiny percentages of weight off the end product, tires. Every little bit counts, and the auto companies, which always want it all from their suppliers as well, want it all: fabulous-performing tires, and make them lighter.

Run-flats still have all that promise going for them: tires that perform fine until they are fixed. Despite that advantage over carrying a spare, the motoring public continues to overwhelmingly vote against the improved technology by ignoring it. The fact that flat tires generally are few and far between, and that little thing called price, gets in the way of a run-flat revolution.

So maybe the tire industry is going about this all wrong.

Instead of expending treasure and time to design lighter - - yet great-performing - - tires, the business should be promoting something like a Jenny Craig for Motorists. Launch ad campaigns with taglines such as "Save Gas, Get off Your Couch and Exercise."

The bottom line: If you want to improve fuel economy for your car, lose some weight. Advice most of us - - yeah, me, too - - should take.

Ed Noga is the slim, trim, spare tire-less editor of Rubber & Plastics News, an Akron-based sister publication of Tire Business. This column was published in a recent print edition of that paper.