WTB Nano SG2 gravel tire review – versatile and tough

The OG gravel tire gets the extra protection it’s always needed but is that enough to make a fit and forget champion again?

WTB Nano SG2 gravel tire
(Image: © Guy Kesteven)

Bike Perfect Verdict

If your gravel biking is like old school mountain biking, then these old school mountain biking tires will work great for you.


  • +

    Reasonable roll

  • +

    Excellent all conditions grip

  • +

    Extra puncture protection


  • -

    Single size only

  • -

    No 29er SG2 protection option

  • -

    Premium price

Why trust BikePerfect Our cycling experts have decades of testing experience. We\'ll always share our unbiased opinions on bikes and gear. Find out more about how we test.

Go back just over 20 years and WTB’s Nanoraptor XC race tire was one of the first designs ever to be upsized to 29in from 26in as part of Gary Fisher’s crusade for bigger diameter MTB wheels. It was also there in a 700 x 40mm format at the birth of his bigger tire ‘Dual Sport’ hybrids a couple of years later. WTB was also super early with the whole ‘Tubeless Ready’ thing. As a result, it was grabbed as the easy go-to option when gravel erupted as a scene and before other tire manufacturers raced to get their own rubber options designed, molded and ready to sell. And it worked great as the same spaced 'V' outer tread and almost continual center rib of forked ‘tree branch’ lugs for fast rolling is quick in a straight line, but tolerably grippy in turns on most surfaces. The trouble was that everyone – including WTB – now had a new range of specific gravel tires to sell so Nano got largely forgotten. Plus, compared to more modern tires, the big bulbous carcass that gave it its float tended to last less time than bit part actors in a slasher movie when the terrain got nasty.

WTB Nano SG2 gravel tire

The tire features a dual compound rubber mix and a flat fiber nylon SG2 bead-to-bead protection layer (Image credit: Guy Kesteven)

Design and performance

Which is where the new Nano comes in. It uses basically the same distinctive dual personality tread, ‘tree branch and wake of lugs’ pattern in a dual compound rubber mix. Crucially, it now gets the option of a 120 Tpi (that’s twice the thread count of previous Nanos) carcass, reinforced with a flat fiber nylon SG2 bead-to-bead protection layer. A few months into all the abuse I can give it, that’s still not been breached despite regular rim on rock pinches and silly low pressures to cope with snow. It only adds 25g over the standard version (50g over the tan wall) too and while 557g is pretty heavy, it’s not far off the ballpark for a reinforced tire that still blows up slightly over its stated size on a 24mm internal rim.

The generous volume means the extra protection doesn’t obviously effect ride quality so it still bowls along nicely with no buzz or rumble. You’ll still have to grit your teeth to keep up with a slick tire on the road, but your jaw will be a lot more relaxed as soon as you hit the dirt. It’s not very directional so you need to stay loose and ready to drift, but ride it appropriately and it holds speed and control fine on sand, loose grit and woodsy singletrack wet or dry. It’ll even have a decent go at paddling through slop if it has to and it’s a lot more predictable when leaned than the cosmetically grippier-looking WTB Resolute. You can change speed and grip vectors significantly by raising pressure to get that center ridge pert or dropping it low to get all the knobs engaged. Either way it holds pressure really well (the SG2 skin also helps stop air leaks/percolation) and the Dual DNA tread is tough in terms of wear too. Be aware that the tan version is still distinctly fragile and porous though and that there’s no SG2 option in the 29x2.1in option that fits big clearance adventure bikes.


WTB has given Nano the confident protection it previously lacked and put this OG gravel tire right back at the top of our fit and forget gravel tire rankings for riders who default to dirt as often as possible. Would be good to see the 29er version get the same SG2 too though.

Tech specs: WTB Nano SG2 gravel tire

  • Price: $76.95 / £54.99 / €64.99 
  • Weight: 557g (SG2)
  • Versions: SG2 (tested), Black, Tan, Race (lightweight tubed), Comp (cheap tubed)
  • Sizes: 700 x 40mm only 
Guy Kesteven

Guy Kesteven has been working on Bike Perfect since its launch in 2019. He started writing and testing for bike mags in 1996. Since then he’s written several million words about several thousand test bikes and a ridiculous amount of riding gear. He’s also penned a handful of bike-related books and he reviews MTBs over on YouTube.

Current rides: Cervelo ZFS-5, Specialized Chisel, custom Nicolai enduro tandem, Landescape/Swallow custom gravel tandem

Height: 180cm

Weight: 69kg