The Panaracer Gravel King tire burst onto the scene last year amid a rapidly growing market in the adventure/gravel scene. The first sizes offered were 700×25, 28, and 32mm, and now they also offer 38mm and increasingly popular 40mm size.
The 25 and 28mm sizes use a file tread while the 32, 38, and 40mm sizes incorporate a unique tread consisting of small square micro-knobs flanked by an almost continuous band of of rubber. This gives the tire an almost inverted tread appearance similar to tires used on hybrid and city bikes.

This review focuses on the 700x32mm size which I’ve used for almost a year now.  The tire features a respectable 320 gram weight, 126tpi casing, and puncture protection belt. The tires mount easily enough although in my case I found they needed to be over-inflated to ensure proper seating, and then let back down to desired pressure.
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After using many tires over gravel rides on both my disc road and cyclocross bike, I fully believe in tires wider than 32mm for these rougher rides. More and more gravel rides seem to be connecting dirt roads using gnarly singletrack or jeep trails only the most capable of Rubicon models could tackle.

For this reason I would only recommend the 32mm size if it’s the largest you can fit in your bike. I was able to shoehorn these into my Focus Cayo Disc but only at lower pressures, and of course they fit just fine in a cross bike.

Out on the road I found the tire casing supple and willing to roll and conform over rough ground. Handling was good with solid confidence pushing through asphalt bends. The crux of this design comes down to the tread design. The tires easily pick up small particles, which my former geologist-self would simply describe as coarse sand. The result is a harmony of pings, tings, and ticks bouncing off your bike. The occasional larger piece will pop off carbon frames with a cringe-worthy audible crack noise. It’s definitely a trait of these tires not seen in other similar gravel tire models. Further, the outer solid tread line apparently keeps those center knobs from fully contacting the ground, and will readily break traction on steep loose climbs where other tires won’t (including some thicker file treads).

The 25 and 28mm sizes are reportedly nice tires for rough New England roads or light gravel rides where 28mm is your max size. However, with so many gravel tires on the market now I can’t recommend the larger Gravel King tires simply for the annoying trait of catching and flinging the road surface into your frame.