First impressions: Panaracer GravelKing Tubeless-Compatible 700x38C

Panaracer recently expanded its size range for the slick GravelKing tires to a 700x38C (40-622) version. Unlike the previous version of the GravelKing, the tire is tubeless-compatible. Availability is still a little spotty, but I managed to buy them from a German online store for about $40 shipped. Given this affordable price and a claimed weight of only 320 grams, they seemed like a good choice for my all-purpose Cross-Check and for our recently acquired tandem. On the Cross-Check I had been running the Vittoria Voyager Hyper (formerly known as Randonneur Hyper) in either 35 or 38 mm width for the past couple years. Those tires used to be available at incredible bargain prices from UK online shops, and they were a great compromise between ride quality and durability. Those online deals seem to have dried up a bit lately, and so I decided to try the GravelKings. I was also curious to try a tire that would be a little wider and, based on the specs, should have a ride quality close to the Compass tires or the Panaracer Pari-Motos I have on my other bikes.

The weight is slightly higher over what Panaracer claims: On the four tires that I weighed with my kitchen scale, the average weight came out to about 335 g, with very little variation between the tires, versus the 320 g claimed weight. Still, this put the tires firmly under the weight of the Compass 700x38C Barlow Pass, which has a claimed weight of 380 g in the Extralight and 430 g for the standard version. The Voyager Hyper in 700x37C has a claimed weight of 395 g, but Bicycle Rolling Resistance measured them at 415 g. So the GravelKing is definitely a very lightweight tire.

Where are the weight savings coming from? Jan Heine from Compass Cycles claims that it's all in the tread thickness: Your sidewalls can only get so thin and supple, but you can easily get lower weight by removing tread rubber (and consequently sacrificing durability). This seems quite plausible: Compared to my Compass Babyshoe Pass tires (650x42B), as well as the Panaracer Pari-Motos, the sidewalls feel slightly less supple. However, both those tires are not tubeless compatible, and people who have tried setting them up tubeless report that the sidewalls are just too porous and keep weeping sealant. It would make sense that Panaracer would add a little rubber to the sidewalls to address this. The tread feels very similar in thickness to the Pari-Motos, and the Pari-Moto tread certainly is quite thin. We will see how long they will last.

Minimalist tread pattern

What about width? I mounted the tires on three different rims, using inner tubes:

• On a DT Swiss TK540 (inner width: 18.2 mm), the tire measured just under 36 mm at about 40 psi. 
• On a Mavic T519 (inner width: 19 mm), the tire measures just over 36 mm at about 50 psi. 
• And finally, on the wider Sun Rhyno Lite (inner width: 22 mm), the tire again came out to just over 36 mm at 50 psi. 

So they're definitely a little undersized. But this is common and they're likely to expand by a millimeter or two over time.

Edit 4/14: After only a week on the bike, the tires have already expanded a bit: On the TK540, they now measure about 36.5 mm; on the wider Rhyno Lite, they have grown to 38.3 mm.

I will report back. Mounting the tires was a mixed bag. Tubeless-compatible tires have a reputation for being hard to mount. And yet, on both the DT Swiss and Mavic rims mounting was very easy and didn't even require a tire lever. On the Rhyno Lite, however, it was nearly impossible to even get one side of the bead onto the rim. With much cursing, sore thumbs, and soapy water I eventually wrangled them on. But this was one of the harder tire mounting experiences I've had. I'm not sure what accounts for the difference, as in the past I haven't had problems with these rims.

Cross-Check with the new tires

I've ridden the tires for only 30 miles so far. They feel very nice and supple, even though I still have to figure out what the best pressure is. The rubber is softer than on the Vittoria tires, providing presumably better grip.

My conclusion for now: These are nice tires at a good price. My final verdict will depend on how long they're going to last. I haven't formally kept track of the lifespan of the Vittoria Voyager tires or my Compass Babyshoe Passes, but they were good for several thousand miles. I don't expect to get quite as much mileage out of these, but I'm not actually tracking mileage and will update this post in the future.