WTB's Horizon TCS is a fast-rolling, super-grippy and super-comfortable tyre that excels on the road and is capable of tackling dry off-road trails to inject some adventure into your routes.
Tyres have been getting wider over the years, and this trend for chunkier tyres and a growing interest in gravel and dirt riding on road bikes has given rise to the return of 650B, an old standard once favoured by French touring cyclists because it allowed bigger volume tyres for more cushioning on rough and badly surfaced roads. (By shrinking the rim size you can use the bigger volume tyre.)
A handful of bike brands big (Cannondale) and small (Hallett Cycles) have been dabbling with 650B and we're seeing a lot more interest from manufacturers of bikes in the gravel and adventure category, where bigger tyres reign supreme. It's all very well having a bike with adequate clearance, but tyre choice is critical.
US tyre and wheel manufacturer WTB is a quick adopter of new trends (it has embraced wide 27.5 Plus tyres in the mountain bike world) and pushed out the Horizon last year. Measuring 47mm wide, they positively dwarf a 28mm tyre – previously considered a pretty wide choice for an endurance bike.
It's a slick tyre, designed primarily for road use, for those cyclists who want to maximise comfort on very rough and potholed roads. The outside diameter is roughly the same as a 700x30, so there's a good chance they'll fit many bikes already on the market (with a change to 650B wheels, obviously), and it also means there's very little impact on the geometry. WTB has a handy compatibility guide here.
The tyre is constructed with an Aramid bead and employs the company's Tubeless Compatible System (TCS), and a dual compound tread with a softer rubber on the shoulders for more grip through the corners. There are four grooves along the tyre tread and a very low profile herringbone file tread pattern.
I installed the tyres on a new 3T Discus Plus aluminium wheelset (review on that soon) with tubeless valves and sealant at the first time of trying, and after some experimenting settled on about 30-35psi as the ideal pressure. That seems crazy low if you're used to inflating tyres into triple figures, but trust me, with extra tyre volume comes the need for less air pressure.
On the road they feel exceptionally smooth. They iron out bumps and holes in the road in a way that no other conventional road tyre I've ever tested does. Almost nothing fazes them, even clattering into potholes doesn't upset the silky smooth ride, and the tyre carcass still feels supple when dealing with sharper impacts.
Away from the relative smoothness of the road, it's surprising just what you can get away with when you point them off-road. Provided it's dry, I was able to tackle all sorts of bridleways, farm tracks, byways, gravel paths – even some tame mountain bike trails in the local woods where I normally take my mountain bike to play on the downhill tracks.
Durability of the tyre has proven to be very good, and even off-road excursions haven't resulted in any punctures or visible damage to the tyre tread. They have a bombproof feeling that positively encourages you to not hesitate in the face of holes and rocks – they can handle it all.
At 522g they're a fair bit heavier than many narrow tyres, but weight isn't everything. At first, especially if coming from a bike shod with 28mm tyres, the weight is noticeable. There's a bit more effort required to build up speed and the weight can be felt through the handlebar – more force is required to initiate turns and they simply aren't as lithe in response as a narrow tyre. But that's to be expected given how chunky the tyres are, and you soon get used to the riding characteristic.
Are they slower than a conventional road tyre? To a degree, yes. On the occasional 60km commute into the road.cc office, I was only a couple of minutes slower on the Kinesis Tripster AT shod with the Horizon tyres compared to my time on a Specialized Roubaix with 26mm tyres, on a route with plenty of different road surfaces and a few hills.
But an important distinction must be made in the effort required to shove the wider tyres through the air. The wider tyres do present an obvious aerodynamic handicap. Simply put, more effort is required to propel them along the road at high speeds, anything up to fast road bike speeds above 35kph and the power requirement noticeably rises. Drop the pace down a bit and you find the sweet spot of speed and effort level.
For taming rough roads and injecting some dryish off-road trails into your route, with better rolling speed than most 40mm gravel tyres, there's a lot to love about the Horizon. It's a great alternative to a wide gravel tyre if you're not intending to tackle very loose and rough tracks, but want a tyre that is faster over a wider range of surfaces, including on the road, and can provide a bit more comfort.
Super-comfortable big-volume tyres with off-road capability
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road.cc test report
Make and model: WTB Horizon TCS Road Tyre
Size tested: 650bx47mm
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
WTB says: "The Horizon Road Plus tire brings supple plus-size traction and smooth riding characteristics beyond where the pavement ends. A smooth centerline and all-weather herringbone pattern with cornering channels make anything possible, just like the size. High-volume road provides deceivingly svelte performance on pavement, with resiliency that isn't shaken by chasing confidants down dusty dirt roads. Sneak it into a cross bike, fit it into a road frame, the overall diameter stays the same as a 700 x 28 - 30mm road tire. Ride it on tarmac, take it to the dirt as well. Creating a new riding experience, regardless of where your exploits lead you.
"Road Plus retains the same geometry as existing endurance road bikes but adds a high volume, tubeless 650b wheel and tire in place of a 700c. With the 650b x 47c Horizon Plus having the same overall wheel diameter as a 700 x 28c tire, it only requires a little more chainstay clearance than a traditional road tire. Match it to a KOM i23 or i25 650b TCS rim and you have a light, high volume, fast rolling setup without going back to the drawing board for frame design."
Tell us some more about the technical aspects of the product?
WTB lists these features:
Wheel Size: 650b
Level: Road Plus TCS
Compound: Dual Compound DNA Rubber
Bead: TCS Aramid
Construction quality is very impressive.
Superbly smooth rolling and comfortable performance on the road, and able to stray into the wilderness provided it's dry.
They've proved to be bombproof, even riding them on mountain bike trails with lots of roots and rocks hasn't fazed them.
Yes they're heavy as a consequence of the extra girth, and you do notice it on the climbs and it does impact the bike handling a little, but you quickly get used to it.
Comfort is their trump card, they are superbly comfortable on rough roads.
They're reasonably priced at RRP and you can get them cheaper if you shop around.
Tell us how the product performed overall when used for its designed purpose
For providing supreme smoothness and the ability to safely tackle off-road trails, the Horizons are highly recommended.
Tell us what you particularly liked about the product
Comfort, smoothness, ability to head off-road.
Tell us what you particularly disliked about the product
A bit heavy.
Did you enjoy using the product? Yes
Would you consider buying the product? Yes
Would you recommend the product to a friend? Yes
Use this box to explain your score
If speed matters, the Horizons aren't the fastest choice, but if your priorities are comfort, cushioning, traction and durability, with speed some way down the list – and your bike can accommodate them – the Horizons are excellent.
About the tester
I usually ride: My best bike is:
I've been riding for: 10-20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: road racing, time trialling, cyclo-cross, commuting, touring, mountain biking
David has worked on the road.cc tech team since July 2012. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds.