Hyundai's Shapeshifting Wheels Create Infinitely Variable Tire Pressures

Apr. 06, 2023 6:29 AM ET by Martin Pretorius Technology / 6 Comments

We've had variable steering and variable compression, but variable tire pressure is the next big thing, according to Hyundai.

Hyundai has developed a means of continually varying tire pressure in a vehicle's wheels, but instead of using an air compressor to adjust on the fly, the brand wants to use shape-shifting wheels. CarBuzz has discovered a patent filed with the US Patent and Trademark Office (USPTO) in which Hyundai and Kia detail a morphable metal to be used on the barrel of the wheel (the outer element of the wheel between the inward and outward-facing lips), which can flex inwards or outwards, changing the shape of the air chamber within the tire, and thus adjusting its pressure.

Think of it like when you squeeze a water bottle - by making the area inside the bottle smaller, you increase the pressure, but when you release it, and the bottle enlarges, there is less pressure inside. Should such a concept see reality, it could just as easily be used on a Genesis G90 as a Hyundai Palisade.

CarBuzz

USPTO

The invention centers around the concept of a bimetallic strip. Bimetallic strips consist of two dissimilar metals rigidly joined together and can be designed to have similar sizes at a specific temperature. When such bimetallic strips are heated, however, their unequal thermal expansion will cause the strips to deform, often bending one way when heated and the other when cooled.

Hyundai wants to use bimetal for the barrel of the wheel, with an electronic controller applying current to the bimetal to prompt it to deform in a convex or concave fashion depending on the conditions. This would enable individual control of tire pressures in each wheel and reduce the frequency at which tire pressures must be checked.

Air pressure in a standard road tire varies widely while a vehicle operates, even without any physical pressure changes being made along the way. Due to the thermal expansion of the air in the tire, a hot tire may experience a pressure increase of up to five psi compared to a cold tire. This can impact ride quality, handling characteristics, and braking capabilities.

USPTO

Conversely, extremely cold conditions can result in denser air and lower tire pressures, which is why you may sometimes park your car in the evening in winter and wake up the following day to a tire pressure warning light, despite no punctures and no overnight adjustments being made.

Tire pressures typically need to be adjusted for driving conditions. A fully-loaded car, for example, requires higher pressures to carry the additional weight safely. In a truck, a heavy payload requires the rear pressures to be upped to compensate. Likewise, driving up a steep incline shifts the weight balance onto the rear tires, and when cornering aggressively, the outer tire is subjected to greater forces but also requires a greater contact patch to enhance grip.

USPTO

Adjusting the pressures in these instances would prevent tire deformation and support the vehicle better. And by reducing tire deformation - like low-profile tires but without the harsh ride - and the larger resulting contact patch, it would improve fuel economy by reducing rolling resistance.

Hyundai's system will rely on feedback from the navigation, weight sensors, tire pressure sensors, acceleration sensors (G-force sensors), outdoor cameras, and even an indoor ultrasonic sensor to determine how many occupants are in the vehicle and use this information to decide which wheel/s needs its/their pressure adjusted and by how much to cope with the conditions at hand.

However, driver-selectable modes will also adjust the pressures, with Eco mode increasing pressure for decreased rolling resistance, etc.

The list of possible functionality created by varying tire pressures is vast.