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Photo: Matt Miller.

Back in March, Pirelli released its first-ever lineup of mountain bike tires. Best known for their car and motorcycle tires, the 100-year-old brand’s entry into the knobby tire market only seemed logical after releasing a road bike tire almost two years ago.

Pirelli came out with a diverse MTB line, with four treads that cover hardpack, mixed, soft terrain, and also a rear-specific tire. Pirelli calls their new MTB tire compound SmartGRIP, and it’s said to offer a temperature-resistant grip and consistent performance in hot, warm, or cold temps whether the trails are dusty or slick.

Specs

  • Rear-specific MTB tire
  • Available in 29×2.2 (120tpi) or 29×2.4 (60tpi)
  • SmartGRIP single-compound rubber
  • Weight: 905g (2.4-inch tested)
  • MSRP: $79 (available at Amazon.com and Wiggle)

About the Scorpion R

The Scorpion R still has some decent tread life after 250+ miles on it. Photo: Matt Miller.

Pirelli takes a unique approach with the classification of their four tires. Rather than giving each individual tire an aggressive moniker that denotes their intent, the Scorpions are all given an individual letter that should draw someone into the right tire for them. S for soft, R rear, and so on.

The Scorpion R takes the relatively new shape of other semi-slick mountain bike tires. Short and tight knobs are packed down the center of the tire, alternating from two to three wide. A row of transition knobs runs between the taller side knobs and the shorter center knobs.

The casing varies between the two sizes with the 2.2-inch getting a 120TPI casing and the 2.4 getting a heavier, but stiffer casing.

The interesting thing to note off the bat about the Scorpion tires is that they are all built around a single compound material, new for Pirelli, called SmartGRIP. By using one single compound, Pirelli says that the performance remains consistent no matter how worn the tire is, rather than a double or triple compound tire which eventually wears down to a harder compound underneath a softer compound.

I reached out to Pirelli to get a bit more information on their compound and durometer, and this was the designer, Fillipo’s response:

“The Shore is a static measure of the hardness at very low deformation, it is a parameter we monitor for puncture and tear resistance of compound. Regarding the Grip and handling we monitor more parameters that give a wider and more detailed picture of the compound: [1] Static stiffness at different elongations [2] Dynamic Parameters: stiffness when the samples are dynamically loaded at a certain frequency, since the tyre is loaded with a certain  frequency while it rotates, and [3] the hysteresis, that is the energy that the rubber absorbs in a loading-unloading cycle. Tuning these parameter the grip, speed, quickness in acceleration and handling of the tyre can be tuned. As reference, the Shore A for the Scorpion R should be around 68.”

The compound is based on over a hundred years of experience developing tires. Each tire gets its own version of SmartGRIP, some harder and some softer, but the idea is the same. Pirelli also says that the compound has been formulated to remain consistent in wet and dry and hot and cold weather.

Performance

The author packing miles on the Scorpion R during BC Bike Race. Photo by Todd Weselake.

I received a handful of tires to check out from a few brands before I outfitted a test bike for BC Bike Race. The Scorpion R seemed like a wise choice to throw in the back. I wanted something with pedaling efficiency for the 200 miles I’d ride during the week, but grip like Pirelli claimed it would have, especially in the wet loam and roots.

Now back at home and fresh off a ride with a different tire than the Scorpion R, the rolling efficiency of the Scorpion R is very noticeable and glides along the trail with grace. In fact, after the test, I feel pretty partial to running a semi-slick tire from now on as the low center knob height eliminates a ton of drag.

The supposed trade-off, of course, is that one would assume that the Scorpion R would be squirrely and slide around like a Swiffer Wet Jet on loose or wet trails without tall knobs to dig into the soil.

Photo: Matt Miller

I didn’t find this to be the case, though. Sure, a knobbier tire like the Scorpion S will offer more grip and traction on soft and loose trails, but the Scorpion R held strong. Testing conditions have ranged from dry, powdery dirt at Granby Ranch in Colorado to a thousand types of loam and wet roots in BC.

During my BCBR week, we had rain and a lot roots for the first five days. After that, there were still a lot of roots, with rock, buff trails, and loose soil. It is possible to get the Scorpion R to break loose, but it remains predictable and the cornering knobs find a lot of traction when the bike is leaned over.

As evidenced in the photos taken the day of writing this review, and after 250-300 miles on the Scorpion R, the wear rate is pretty darn good. The tread-siping is still visible and the center knob edges aren’t really rounded out yet. The tire did get a small puncture however, after at least 250 miles when I went air to rock. It’s a small puncture, and a plug would probably hold it together for another 50 miles, but I feel content with what the Scorpion R has accomplished.

Final word

Photo: Matt Miller

As a rear-specific mountain bike tire, the Pirelli Scorpion R performed admirably during my testing time with it. It rolls efficiently and performed consistently through the conditions that I rambled through, from dry and buff to wet and loose.

Thanks to Pirelli for providing the Scorpion R tire for testing.

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