Kumho Australia managing director Yoon Hong Kim and head-office engineer Hyungwoo Kim have been in New Zealand to oversee the installation of a trial set of Kumho KCA31 EV bus tyres, in a programme run with Kumho’s New Zealand distributor, Blairs Supertyre Distributors.
The trial addresses a straightforward problem. An electric bus keeps its tyres under load in both directions — under the torque of the electric motors on acceleration and again under regenerative braking — and the bus itself weighs considerably more than its diesel equivalent. As a result, a standard bus tyre wears much faster. Where a diesel bus might see around 120,000km from a tyre, Blairs says an EV bus running the same tyre may manage only about 40,000km.
The KCA31, sold in Europe as the K E-City CA31 and launched in August 2025, is built for the start-stop duty of an urban electric bus. Its compound is formulated for low rolling resistance, which on an EV translates directly into energy consumption and range as well as mileage. A three-by-five rib tread pattern is designed for traction and stability under the constant load cycling of electric drive, and the casing is reinforced through the sidewalls and centre ribs to carry the extra battery weight and resist the scrubbing that kerbs and tight urban routes impose. A sidewall wear indicator, specific to bus use, gives operators a quick check on kerb-strike and scuff damage. The tyre is also rated for diesel and hybrid buses, so a mixed fleet can standardise on it.
The first size to market, and the one on trial here, is 275/70R22.5 with a 152/149J load and speed rating; 315/60R22.5 and 265/70R19.5 sizes are to follow.
The KCA31 extends into commercial fleets the approach Kumho has taken across its passenger EV range, which Blairs also distributes: the ECSTA PS71 EV, CRUGEN HP71 EV, and SOLUS HS63 EV, plus the EV-compatible ECSTA PS72 SPORT. All share reinforced construction for battery weight, compounds tuned for instant torque, low rolling resistance, and noise reduction through tread design and, on the passenger tyres, K-Silent foam.
Blairs will monitor the trial set’s performance against the fleet’s existing tyres. The aim is to show that a tyre designed for the application delivers a lower cost per kilometre and better overall performance than a conventional bus tyre pressed into EV service.
For more information, visit blairs.co.nz
