New high-speed Panaracer GravelKing ZX is its 'fastest ever tyre for mixed terrain'

A new three-zone tread pattern is designed to optimise rolling and handling on changing surfaces

Photos: Andy Donohoe/Commuter Films Words: Simon Smythe

Gravel has come a long way, and so has Panaracer’s GravelKing tyre since it launched in 2014. At the start, gravel was just a few people riding for fun on agricultural roads in the Midwest away from the traffic. Now it’s a full-blown international discipline of its own and is increasingly focused on performance – without leaving the fun entirely behind – and which requires equipment to evolve along with the increasing average speeds and the more challenging mixed surfaces of international races. Panaracer is itself the headline sponsor of the UCI Gravel World Series, so it has a direct interest in developing fast racing rubber.

Enter Panaracer’s new GravelKing ZX, a tyre with a three-zone tread pattern that the Japanese brand says is “engineered to maximise speed while preserving confident handling across varied terrain”.

At the centre is a smooth, almost road-like pattern that is designed to minimise rolling resistance and maintain momentum on tarmac and hard-packed gravel. Meanwhile, the inner edge uses a “transitional tread” that engages under braking and leaning into corners, maintaining grip and enabling a predictable feel. On the outer edge of the tyre, aggressive side lugs are positioned to provide traction needed for cornering on loose gravel, technical descents and much rougher surfaces.

According to Panaracer, these three zones allow the ZX to maintain speed where it matters most while delivering the feel and confidence gravel riders expect. It lists events to which the new tyre is suited, including of course the UCI Gravel World Series and the other marquee events such as Unbound, the Traka, Sea Otter and Dirty Reiver.

It’s not just the tread pattern – the new ZX tyres use a new ZSG (zero slip grip) compound that Panaracer says is purpose built for gravel and is backed up by its testing. Tyre brands are always secretive about compound recipes so there’s no more information than that, but the brand adds: Consistent with Panaracer’s long-standing compound philosophy, the ZX uses a single compound formulation to maintain predictable ride characteristics and long-term durability.

A Tufftex casing – a high-thread-count supple structure already in use with existing GravelKing tyres – protects against punctures, while Panacer’s BeadLock is designed to keep the bead stable at very low pressures and works with both hookless and clincher rims.

The ZX went through six mould iterations before the final version went into production, something that Panaracer says allowed its engineers to refine the tread profile, grip characteristics, and ride feel until the tyre achieved the perfect balance.

And finally, no new GravelKing tyre launch is complete without a word from Jeff Zell, the product manager – officially Panaracer’s “global go-to guy” who conceived the original version 12 years ago, when it was available in 23mm or 26mm, huge for the time. He even came up with the GravelKing name. We interviewed him in 2024 when Panaracer launched a revised, updated GravelKing range on its 10th birthday and he told us the story of how he convinced his Japanese bosses, who hadn’t heard of gravel riding yet, to launch the GravelKing.

About the new ZX, he says in the press release: “We’re excited to introduce the GravelKing ZX as the next evolution in our GravelKing range. Designed for today’s mixed-surface riding, it delivers race-ready speed alongside the grip and durability riders need when conditions become unpredictable.”

It’s true he has said more illuminating things in the past, but reading between the lines, the new ZX is doing something akin to what the original GravelKings back in 2014 were doing. About those, Zell told us: “[The terrain] may not technically be gravel but you want a more comfortable ride. Maybe you’re looking for something offering a bit more comfort that doesn’t feel like you’re on a shopping bike.” Today’s gravel race bikes in no way resemble or ride like shopping bikes, even without the latest tyres, but what he’s saying is that the new ZX gives gravel racing tyre development another significant nudge into the future.

We have a set on test, so stay tuned for our review.