A NASA-affiliated company set up to develop a new category of tire could be one small step closer to a giant leap for the future of transportation.
The SMART Tire Company (opens in new tab) was formed with the aim of commercializing an airless alloy tire called METL (Martensite Elasticized Tubular Loading) that was originally invented for space exploration. SMART is an acronym for Shape Memory Alloy Radial Technology.
“Starting with the extreme capabilities of this Mars-grade technology, we’ve developed new, patented tires designed for cycling, automotive, trucking and aerospace applications,” the US brand claims.
SMART’s approach appears to be the polar opposite of existing puncture-proof tire manufacturers such as Tannus (opens in new tab)whose solid tires are made of a micro closed cell polymer resin (MCP) manipulated to make a solid foam-like material.
The innovation by the NASA Glenn Research Center comprises a “non-pneumatic, compliant tire utilizing shape memory alloys (mainly nickel-titanium alloy NiTinol) as load bearing components.”
Shape memory alloys deform and then spring back to their original shape. The science says they are capable of undergoing “phase transitions at the molecular level with significant reversible strain (up to 10%), an order of magnitude more than ordinary materials, before undergoing permanent deformation.”
Commonly used elastic-plastic materials such as spring steels and composites can only be subjected to strains of around 0.3-0.5% before suffering plastic deformation, according to SMART.
Which means the use of a nickel-titanium shape memory alloy ought to produce a tire that is elastic like rubber yet strong like titanium – and obviously doesn’t need air and therefore can’t flat.
SMART claims the use of memory metals provides enhanced control over the effective stiffness as a function of the deformation, giving increased design versatility. For instance, it says, the tire can be made to soften with increased deflection, reducing the amount of energy transferred to the vehicle or bicycle during high deformation events.
The company says the final product will be integrated with “a special poly-rubber material for the longest-lasting tread and grip for all weather conditions.”
However, despite the METL tire’s claimed longevity and durability, it seems clear that it could have sizeable disadvantages compared to pneumatic tires: firstly it won’t be possible to adjust pressure for rider weight or terrain.
Additionally SMART has not provided any rolling resistance data – surely an oversight since the entire focus of increasingly wider pneumatic bicycle tires has been on this.
We don’t know how much the METL tire with its poly-rubber tread will weigh.
And there’s also no detail on rim compatibility. When the original METL tire was unveiled in 2021, the company was reportedly working to make it eventually backwards compatible with a standard clincher rim, although the prototype was mounted on a tubular rim.
And once the poly-rubber tread on the alloy carcass wears out, how and by whom will it be replaced?
And finally, last year the cost of a pair was estimated to be around $2,000 – that’s prohibitively expensive, even if they do last the life of the bike.
In 2021 US bike brand Felt announced it was partnering with SMART. Eric Sakalowsky, Felt’s VP Global Marketing & E-Commerce, was quoted as saying: “The SMART Tire Company’s tire solution shows an exciting new frontier, and we’re excited to offer our bikes to support their testing.”
SMART says it has the commuter, road, gravel, mountain bike and e-bike markets in mind, and says the METL tire is a “high-value product for the modern bike enthusiast and pro level cyclist.”
But at the moment it seems as though the e-bike market will be the best fit for it, where a tire’s toughness rather than its performance is the priority.
And there’s still no on-sale date for the METL bicycle tires despite the company exhibiting at the CES tech show in Las Vegas earlier this month, announcing partnerships with automotive manufacturers Kia and Hyundai and being recognized for two different CES 2023 Innovation Awards for vehicle tech and sustainability.
SMART has even loftier ambitions, with its tires likely to head back into space. It claims it has created the ultimate lunar tire, capable of carrying multiple astronauts plus cargo across the south pole of the moon as part of NASA’s Artemis Program (the manned return to the moon). Additionally, it says it has already been contracted by some of the largest private aerospace companies in the world, to aid in their efforts towards the exploration and commercialization of space.
Back here on earth we’ll wait to see how its bicycle tire program unfolds. And if you want to invest in the technology you can do so via its website (opens in new tab). Of a $4,920,000 target $432,455 has been raised so far.
If you’re after a reliable tire and don’t want to wait for SMART to come to market, make sure you check out our buyer’s guide to the best puncture-proof tires for cycling (opens in new tab).