Wil Reviews Pirelli’s Off-Road Rubber
Pirelli may be best known for its involvement in high-performance motorsport, but more recently the Italian rubber manufacturer has also turned its hand towards the world of pedal-power. In addition to producing tyres for road racing and gravel bikes, last year Pirelli unveiled the Scorpion MTB tyre range – the brand’s first foray into the mountain bike market.
Pirelli’s approach is a little different to other tyre manufacturers. The range is made up of four distinctive tread patterns, each of which are designed to excel in different conditions. The four models include the Hard Terrain (H), Mixed Terrain (M), Soft Terrain (S) and Rear Specific (R). We covered the full Scorpion MTB range in our detailed first look article, which includes an overview of all of the available options.
In this review, we’re going to take a closer look at the tyres we’ve been riding for the past four months, the Scorpion M and the Scorpion R.
Pirelli Scorpion MTB Mixed Terrain Tyre
The Scorpion M is Pirelli’s all-rounder. It features a medium tread profile and is designed to work across mixed conditions, from hard-to-soft, and dry-to-wet. You can get the Scorpion M in 27.5in and 29in diameters, and 2.2-2.6in widths.
Like all of Pirelli’s mountain bike tyres, it uses the SmartGRIP rubber compound. Pirelli doesn’t disclose the specific durometer or makeup of its rubber blend, but it does state that the compound is different throughout the range, depending on the application. And unlike other high-performance mountain bike tyres that layer two, three or even four different types of rubber through the tread blocks, SmartGRIP uses just a single compound. We’re normally used to associating a single compound tyre as being the cheap wire-bead version, but Pirelli insists that its cooked up quite a special recipe with its unique rubber blend. It also states that this single rubber compound provides greater durability and a more consistent wear rate throughout the life of the tyre.
We’ve been testing the Scorpion M in a 29×2.2in size, which uses a supple 120tpi casing that is reinforced with extra strips of 120tpi Nylon along the sidewalls. You can also get this same tyre in a LITE version, which ditches the sidewall reinforcement to drop 40g per tyre. Given the pointy rocks around my home trails though, I elected to go for the standard and slightly heavier version.
Pirelli says its 2.2in tyres are optimised for a 25mm wide rim bed. I’ve tested the Scorpion M on the 24mm wide Hunt Race XC Wide wheels, 25mm wide Reynolds XC259s, and 27mm wide Santa Cruz Reserve rims. In all cases they’ve aired up tubeless easily with a floor pump, and they’ve held pressure very well.
All our test tyres measured up pretty much as claimed, coming in at 743-746g on the scales and measuring 2.27in wide.
While I’ve mostly run the Scorpion M as a front tyre, I’ve also fitted it to the rear as well. Pressures have varied accordingly, and also depending on the terrain at hand. I’ve gone anywhere as low as 20-23psi on the front, and 24-26psi on the rear.
For a XC/quick trail tyre, the Scorpion M has proven to be a superbly versatile and predictable performer. Compared to the 2.3in Specialized Ground Control GRID tyre that came off the front of my bike, the Scorpion M not only feels more stable, it also feels more consistent through its contact patch. The profile is neither too square, nor too rounded, with a gentle curve that throws up no surprises when you’re banking from left to right.
The micro-knob tread pattern doesn’t look all that revolutionary, but that doesn’t seem to be a problem either. There are plenty of biting edges, and the slightly deeper cornering blocks use a flared base that helps to stabilise them and minimise squirm through the turns. Overall Pirelli has struck a nice balance between weight, casing stability and damping, which means the Scorpion M doesn’t flop about when pushing hard – something that lightweight high-TPI tyres can struggle with. Because of its stable structure, you’ve got more freedom to drop pressures and not be penalised for it.
Rolling speed is good, though there are faster tyres out there – including Pirelli’s own Scorpion H, which is optimised for buff hardpack trails. For the racer types, pairing an M up front with a H out back would be a sweet combo.
Where the Scorpion M really excels is on technical hardpack trails and hammering over big embedded rock gardens, where its nicely-damped casing, sticky rubber and micro knobbies ensure there’s plenty of surface contact with the ground. Sharp surprise rocks don’t phase it, and the more I rode it, taking more brutish lines became less of a gamble. When the surface is sandy or loose-over-hard, the Scorpion M does well to hold on longer than you’d expect those tiny knobs to do so. And when it does break traction, it does so in a linear fashion with minimal panic. This differs to my experience with the Ground Control and Maxxis Ikon tyres, which have a greater tendency to skip out rapidly once you push past the grip threshold. In comparison, the Scorpion M rarely gives up completely, and I was also able to bring it back from drifting numerous times, albeit with a slight lift in heart rate.
Wet Weather Riding
Perhaps the biggest surprise with the Scorpion M though was in wet conditions. Pirelli makes some bold claims about its SmartGRIP compound and its adaptability, claiming that there is no compromise in grip when it’s wet, and that “it’s finally no longer necessary to select a different tread in the event of poor weather”. That’s a bit of a stretch. When faced with goopy mud, the Scorpion M doesn’t magically turn into a mud spike. In those conditions, there’s no getting around the fact that the tread is quite shallow and there’s little room between the knobs to effectively shed mud. If wet, sloppy, mud-splattering trails are on the agenda, the toothier Scorpion S (Soft Terrain) will simply provide more mechanical grip than this tyre.
However, during an unexpectedly moist ride around the Wombat Forest in Woodend, a place that is lethal in the wet thanks to its plethora of shiny roots and sections of clay-based soil, I experienced none of the slipping and sliding I was expecting. In fact, my ride time was basically the same as it was in the dry. Even as I passed over angled roots, shiny rock slabs and over large sodden logs, the Scorpion M showed no sign of letting go. Miraculously I didn’t crash once – any other micro-knobby tyre would have had me on my arse in a heartbeat.
While I first thought Pirelli’s claims of ‘chemical grip’ were hogwash, I’ve changed my tune following several wet-weather experiences. I can’t think of any other explanation, other than whatever special sauce Pirelli has poured into its SmartGRIP compound, it works.
I’ve been thoroughly impressed with durability too. Tread wear is exceptional given the mileage, and I’m also yet to experience any punctures, sidewall cuts or any torn knobs after four months of use on the hard and rocky trails around the Goldfields region in Victoria. I’ve also got two other riders on Scorpion M tyres, who have both been running them hard-out for 9 months, which has included a tonne of XC and XCM racing all around the state. Only one tyre has punctured in that time, and that was from a metal screw that was picked up while riding on the road.
The Scorpion M’s durability compares favourably to the popular 120tpi Maxxis Ikon/Ardent Race tyres, which are significantly more prone to pinch-flats and sidewall tears, even with the EXO casing. The Pirellis have not only lasted considerably longer, there’s also been minimal, if any deterioration in their performance over that time. These are tough, well-wearing tyres.
Pirelli Scorpion MTB Rear Specific 29×2.2in Tyre
As its name suggests, the Scorpion R is a rear-specific tyre that is also designed for mixed conditions. This makes it an ideal pairing with a Scorpion M up front, which is exactly what I’ve been running for the past few months.
You can also get the Scorpion R in both 27.5in and 29in diameters, and in widths from 2.2-2.6in. However, since rear tyres experience much higher loads than a front tyre, Pirelli doesn’t offer the Scorpion R with the unreinforced LITE casing option. It does get its own SmartGRIP single rubber compound, which is layered in a micro-knobby tread pattern that sees staggered cornering blocks interlinked with wide-face, slightly ramped rectangular centre blocks.
Our 29×2.2in test tyres came a little over the claimed weight (773g vs 740g), and they measure a lick wider too at 2.25in. I tested the Scorpion R on the same rims as the Scorpion M, so rim widths varied from 24-27mm. Predictably, it felt a touch stiffer and more direct on the wider rims, and a little floatier and more comfortable on the narrower rims.
Weighing 67kg, I set pressures between 23-25psi to hold firm on my rocky local trails. However, one of my fellow testers who’s a similar weight to me, has been running pressures as low as 21psi on his buffed-out coastal singletrack. He does ride with a much smoother cat-like finesse though.
Compared to the Scorpion M, which I also used as a rear tyre, the Scorpion R is noticeably slower rolling. It’s a touch heavier, but the wide centre tread blocks and more broadly spaced cornering blocks increase surface friction, which you can feel both on the road and on the trail. As mentioned above, if you’ve got XC racing aspirations, you’ll get a zippier setup with a Scorpion M front and rear, or with a Scorpion M/H combo.
It’s on sketchier trail surfaces where the Scorpion R starts to shine though. In a similar fashion to the Scorpion M, it gives a nice, predictable feel on rough and rocky hardpack trails, and it also seems to be relatively ambivalent about wet conditions as long as it’s not gloopy. In direct comparison, it is a slightly stiffer and more firmly damped tyre, and I felt more confident slamming the Scorpion R into rocks and ledges on the trail when my line choice didn’t quite pan out.
It also has superior braking traction. This is the flip-side to those wide centre tread blocks, which angle backwards slightly to increase bite when you’re hitting the anchors. The result was a distinct lack of skidding under panic-braking. I could still get it to drift if I wanted, but it was far less likely to accidentally lock up and send the back wheel out sideways.
The bigger cornering blocks give more stability through the turns too, something that was made apparent when I switched back to a Scorpion R after riding the M on the back for a while. The profile is also slightly more rounded on the Scorpion R, and that makes it more willing to lean-in to the corners where it continues to hold tight even when things get loose. Even more impressive is that when you’re really pushing into tight turns on dusty singletrack, the Scorpion R has an ability to pivot sharply while engaging in a small but controlled drift, exactly when you need it. I suspect this has to do with the broad spacing between the shoulder blocks, which allows for some flexibility through sharp corners, before the blocks hook up again as you straighten up past the apex.
The overall result is a more secure feeling at the back of the bike. Rear grip isn’t something that many riders think about when favouring a more minimalist and faster-rolling rear tyre. I really enjoyed that added reliability though, and it gave me more confidence to stay off the brakes for longer and lean the bike in harder. Depending on the racecourse, that improvement on the technical sections could potentially find you more time than whatever you’d save having a faster-rolling rear tyre.
The only area that myself and other testers found the Scorpion R lacking compared to the Scorpion M was during technical and loose climbing sections in the wet. The centre tread blocks are a touch too shallow and close together to get decent purchase on wet roots and rocks, leading to more wheelspin under high torque loading. In this scenario, the Scorpion M does give you more biting edges.
As with the Scorpion M, I’ve given the Scorpion R a helluva time of the past four months, and my fellow testers have been rolling on the same tyre for a few months longer than that. None of us have managed to puncture the Scorpion R yet. Quite amazing really given the local trails’ ability to shred tyres and pummel rims.
The cornering tread is starting to show some wear, and some of the casing threads are becoming visible on the sidewalls. Still, I’d estimate they’re only about halfway through their usable lifespan, and they’ve worn considerably better than an equivalent Maxxis 3C MaxxSpeed tyre. It’s also worth mentioning that as per Pirelli’s claims on its SmartGRIP compound, the Scorpion R has been consistent and thoroughly reliable throughout that time.
Flow’s Final Word
Given there’s nothing overtly different about the tread design, I can’t say I had any specific expectations about Pirelli’s tyres coming into this test. I was pleasantly surprised by the versatility and reliability of both the Scorpion M and Scorpion R tyres though, which have delivered exceptional performance and durability.
The casing achieves a near-perfect balance between stability and damping, allowing you to run lower pressures without everything getting too wobbly. And the SmartGRIP compound proves that high quality rubber can make all the difference to traction and feel. Not only does it perform through a wide variety of conditions, it also wears incredibly well.
Certainly for those after a versatile tyre setup for XC riding that’ll stand up to plenty of hard and fast riding, I can’t really think of many better combos than this.
Mo’ Flow Please!
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