Review: Panaracer GravelKing 700x38C (40-622)

It’s time to update my first impressions on the Panaracer GravelKing Slick tires. I’ve ridden them on my fixed-gear Surly Cross-Check for a full season, from April to November 2018. Over that period, I rode about 3000 km (1900 mi), much of it for commuting and riding around town but also on camping trips hauling a trailer or the Lake Monona 100. In November I switched to my studded winter tires, and now that spring has returned to Madison, the Gravel Kings are back on the bike.
This post will focus on ride quality, number of flats, width, and wear.

Ride quality

I have little to say about ride quality—and that’s a good thing! Jan Heine of Bicycle Quarterly makes the argument that a good bike (and consequently good components) disappears under its rider. There are no annoying noises, the tires don’t feel harsh, they corner well, and they don’t seem to slow me down. They also don’t feel overly sensitive to pressure, which is nice for a bike that gets ridden every day. Usually I pump up the tires to 2.7–3 bar (40–45 psi) and then only top them up when they look really low, which could be as low as 1.7 bar (25 psi). I hesitate to make more quantitative statements about how “supple” or “fast” the Gravel Kings feel. I don’t believe that the subjective feel of those qualities is at all reliable, and I haven’t done any quantitative testing. But as I said: They certainly don’t feel slower than any of the other high-quality tires I have in my fleet, including Compass/Rene Herse tires with regular casing and Panaracer Pari Motos.

Width

Hard to keep the calipers straight and camera in focus at the same time...

In the comment section of my first impressions post, several people asked whether the tires grew in width over time. As a reminder, these were the measurements right after mounting them:

• 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. 

As I mentioned in an update to the previous post, within a week the tires had grown by 1–2 mm. So how wide are they now? At 50 psi (as displayed by my pump’s gauge), the tires measure somewhere between 38 and 39 mm on both the Rhyno Lite and TK540 rims. For a tire labeled 700x38C* (40-622), I’d say that’s true-enogh to size. (If you want to learn more about tire sizing and tire size labels, I recommend the article “Tire Sizing: A Mysterious Art” in the latest issue of Bicycle Quarterly).

* Technically it should be 700Cx38, but this is a common labeling mistake nowadays.

Wear and Flat Resistance

Former front tire, now in the rear. Center tread still visible

Before remounting the tires this spring, I closely inspected the tread. One of the downsides of running full fenders is that it prevents a quick visual inspection of the rear tread—which of course is the tire that wears quicker. And indeed, on the rear tire the center tread had clearly worn away. On the front, the little tread dots were still visible, and so I decided to switch front and rear tire. I haven’t noticed an increased number of flats, and in general I have encountered few flats  (even though I did have one just two days after reinstalling the tires in the spring...). Frequent flats are one of my main indicators for replacing the tires. The casing is in excellent shape still, despite me lock up in public and the above-mentioned carelessness about tire pressure. I’m hoping to get another 1600 km (1000 mi) out of this set of tires, but we shall see.

New

One somewhat related observation: In my first impressions, I mentioned that installing the tire on the Rhyno Lite rim was nearly impossible. This has gotten much better and I can now mount and dismount the tires without tire levers. I have not tried setting the tires up tubeless and I have no plans of doing so.

After 3000 km (this is the rear tire): Center tread is mostly worn away

Overall verdict

I don’t regret buying these tires at all. My main concern had been wear. And so if the GravelKings do indeed hold up another 1600 km (1000 mi), for a total of about 4500 km (2800 mi), that’s good enough for me. I would probably still replace them with Compass/Rene Herse tires, mostly so that I could compare the cost per mile over the lifetime of the tire. At market price, the Rene Herse tires are over one third more expensive, and I think it's possible that I could one third more miles out of them. If it is close, I’d always opt for the more durable tire for environmental reasons.

PS Please note that within the GravelKing series, there seem to be substantive differences in tire construction based on size. Especially the 650B x 48 (48-584) has gotten some bad reviews and is much heavier compared to the Rene Herse tire in the same size.