The newest fitness tool coming to a gym near you looks like a tire stolen from an alien automobile. But more important, it resembles the love child of the step and the Bosu, two of the most popular pieces of exercise equipment in recent history.

Even if you’ve managed to avoid sweating for years, you’re probably at least acquainted with the cardio-conducive step platform and the blue squishy domes meant to test your balance. The two concepts are melded in the form of Step360, which fitness company Gaiam recently debuted at a convention in Los Angeles.

It was conceived in 2006, when entrepreneur John Cole was practicing karate at his San Diego dojo, and he wanted to find a more challenging way to practice standing on one leg while kicking. He glued two inner tubes together and topped them with a plank of wood, and the basic idea was launched — and was more effective than he ever imagined. The wobble forces your core muscles to engage, while the surface on top allows users’ feet to be level, which mimics the real world.

Gaiam teamed up with Cole because he’d stumbled across the ultimate combo of the familiar and the innovative, says company president Bill Sondheim. Gaiam, which gussied up the concept by developing a sleeker, easier-to-mass-produce device, sees endless potential among consumers, particularly baby boomers.

“The largest demographic is the slightly aging group looking for fresh, new ways to exercise that are safe and not intimidating,” Sondheim says.

Fabio Comana, a professor of exercise science at San Diego State University, noticed in research on Step360 that it filled a gap.

“When I was looking at conventional balance-training devices, I saw they were too advanced,” says Comana, who is also an exercise physiologist with the American Council on Exercise. His progression for students looking to improve their balance had been: solid ground, an Airex pad (made of a foam you sink into) and then a Bosu. “That’s a leap of faith,” he says, since a curved surface is much more treacherous.

(Expect infomercials by January, and you’ll be seeing Step360 in stores such as Target, Walmart and Dick’s Sporting Goods in fall 2011.)