The Onza Porcupine RC is their most aggressive-looking mountain bike tire to date. Aimed at downhill and e-MTB, the Porcupine RC gets a more open tread pattern and a tougher casing to handle the increased demands of gravity riding. Openly admitting that the Porcupine RC has high rolling resistance, this Onza downhill tire prioritizes cornering characteristics over everything else.
We break down the new Onza downhill tire into its constituent components.
Onza Porcupine RC MTB Tire
Onza pitch this aggressive gravity-focused tire as “Rough Conditions” tire. Granted, that’s a little vague. It is mountain biking after all. They do go on to describe the tire as more suited to wet or loose soil conditions, as opposed to smooth or loose over hard pack surfaces.
Onza rate the Porcupine RC’s rolling efficiency at 1/5, but the cornering control at 5/5. With an ETRTO of 63-622, the tire is 2.5″ wide. It is optimized around internal rim widths between 28mm and 35mm.
The Onza Porcupine RC is pictured here as a front and rear tire, with no specificity or marketing bias towards either. However, based on the aggressive widely spaced tread pattern, soft compounds and high rolling resistance described, we reckon this tire would likely serve riders best on the front wheel.
Onza Porcupine RC Tread Pattern
The Onza Porcupine RC loses the busy tread pattern of the Porcupine Trail released last year, replaced by a much more open tread with more defined centre and outside knobs.
At the centre, we see a repeating sequence of three pairs of blocks. The first pair sit close together, with a low profile bridge connecting them. The second pair are a little further apart, with no connector. The third pair, also with no connector, are further apart again. This final pair of centre blocks are siped to allow a little deformation or flex. The sequence then starts over.
An uninterrupted channel exists between the centre tread and outside knobs which gives the tire a substantial edge for cornering.
The new Onza downhill tire has two alternating types of outside knob. Both stand tall to offer good bite. One type is siped in the direction of travel. The other is braced by additional rubber on the inboard side. Onza say this reinforcement will prevent the side knobs folding under harsh cornering.
Dual Compound Rubber
The Onza Porcupine RC tread uses a combination of 50a and 45a rubber compounds. Together, they call it GRC 50. Both compounds are on the softer side, relatively speaking, but the centre tread makes use of the harder 50a for its faster rolling properties and durability.
The outside knobs are made up of the super soft 45a rubber chosen here to prioritize traction and cornering control.
GRC Gravity Casing
The Onza Porcupine RC features their new GRC Gravity Casing. The tire is still made up of a 120 TPI single-ply casing, as you’ll see on the Porcupine Trail. These two pieces of single ply material overlap at the tread pattern area.
To make the tire a bit meatier, i.e., stiffer side walls and more puncture resistant, Onza have added a couple of key layers to the casing. First up, they’ve added 2-ply reinforcements at the innermost portion of the casing. At the foldable Kevlar bead, they’ve put a bead reinforcement layer. Finally, butyl inlays sit between the bead reinforcement and 2-ply reinforcement layers.
Pricing & Availability
The Onza Porcupine RC is available in one version only. It’s 29″, with GRC Gravity Casing and the GRC 50 compound. No word from Onza as to whether they will offer a harder compound version in the future.
We almost forgot! Bang in the centre tread of the new Onza downhill tire is a low profile Porcupine. Add this prickly character to your ride for 79€ / $79. Available now.