Why do tires have to be filled with air?

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This is an issue that has perplexed me for most of my life, because pneumatic tires filled with air seem like the last anachronistic, 19th-century component of a modern automobile, and an idea which should have disappeared many decades ago. In an era where even the internal combustion engine itself is giving way to electric motors, and where a new economy hatchback has exponentially more computing power than the Space Shuttle, pneumatic tires don’t seem to make sense any longer.

(And before I get flamed, I KNOW modern tires are vastly more advanced and reliable and capable than their 1930’s counterparts. “Blowouts,” which were a common occurrence when I was a kid, are pretty much unheard of today. Modern tires are great. But they are still vulnerable and maintenance intensive in a way that doesn’t make any sense to me.)

Companies have experimented with non-pneumatic passenger vehicle tires in the modern age. One of the primary drivers for a while was Michelin. But the tires weren’t filled with solid rubber. In fact, they didn’t even have sidewalls. They were open on the sides, and they had a support lattice of structural polyester ribs, with a ton of air space between the contact patch and the (now deformable) wheel. Odd looking things.

One of the big problems with switching from pneumatic tires to non-pneumatic tires is the fact that the current air-filled tire is an important component of the suspension of a vehicle. The flex in the sidewall is a critical part of the compliance of the suspension and affects ride and handling substantially. (Which is why racing drivers sweat tire pressures at each corner of the vehicle so much. Even a small change in tire pressure can have a big effect on the handling and grip of a vehicle.) So if a company like Michelin wants to make a non-pneumatic tire, it helps the finances of the program if the new design mimics as closely as possible the compliance and flex characteristics of the outgoing, air-filled model. If it does, Michelin would be able to sell the new non-pneumatic design as a retrofit to older vehicles whose suspensions were originally designed with pneumatic tires in mind. And that is huge, because if they can’t, it becomes a much bigger problem to convince manufacturers to change over to the new design, particularly after the mild debacle of Michelin’s failed “TRX” metric tire idea of the 1980’s, which required the use of a special wheel, and which, despite being by most accounts a superior design in almost every way, never really took off. (Owners of 1980’s Ferrari 512 Berlinetta Boxers and some Saab 900 turbos will know what I’m talking about here.)

These non-pneumatic Michelins are also rather weird looking, and it’s not clear which manufacturers, if any, would take the risk of being the first to offer them on a new car.

So I think that is the issue. Any non-pneumatic tire design must be not only clearly superior to the pneumatic deigns of the past, but it must be functionally identical to the outgoing models they would replace, and they must be visually acceptable to consumers.

I hope it happens, though. I hope someone cracks the nut. Pneumatic tires are a 19th-century application still being used on 21st century vehicles, and at some point that needs to change.