The Nano Raptor has been in WTB’s tire arsenal for decades. It's a favorite with cross-country racers and has been the tire of choice for grueling endurance events such as the Tour Divide. The Nano 40c is a scaled down version of this venerable tread design and is supremely suited to mixed-surface rides and gravel racing.
As the name implies, the Nano 40c has a claimed width of 40mm. Our test tires actually measured in at 41mm, so you get one more millimeter than you’re paying for on rims with an internal width of 20mm. The actual weight for our test tires was 535g each, which is respectable for the category.
WTB offers the Nano 40c in this tubeless-compatible version as well as folding and wire bead versions designed for use with inner tubes.
The high-volume, tubeless-compatible casing does an impressive job of balancing ride quality with durability. While the Nano 40c is designed as a gravel tire, this tester was also impressed with its performance on singletrack.
It was the tire I ran for the Grinduro, which is a gravel stage race that includes miles of chunky gravel and even some rugged singletrack. In these conditions, the Nano 40c shines. The open tread and ample side knobs inspire confidence through the corners and provide plenty of braking traction when needed.
This shouldn’t come as much of a revelation, considering the fact that WTB repurposed a legacy mountain bike tread pattern to create the Nano 40c.
This off-road performance does come with a trade-off. The Nano 40c rolls surprisingly fast in a straight-line, thanks to the nearly continuous raised center tread and decidedly round profile, however the steering becomes vague as the side knobs start to squirm on pavement.
But this isn’t a road tire, after all, and while there are smoother treads on the market, few offer the same the level of versatility as the WTB Nano 40c.
If your all-road adventures consist of a mix of pavement and hard-packed dirt roads, there are faster-rolling file tread options to consider. However, if you like to take your drop bar bike on a mix of loose gravel and singletrack, the WTB Nano 40c is an excellent choice.