Well, you learn something new every day. In this case, the “you” would be me and my use of the word sipe. I’ve been using it for years to mean the grooves in a tire’s tread pattern. (Several online dictionaries, the one built in to my laptop’s OS, and the dictionary of record, the Oxford English Dictionary, confirm this by saying “a groove or channel in the tread of a tire to improve its grip.” But I digress.) What prompted this discovery was a statement made at the beginning of the press briefing for Michelin’s introduction of the Pilot Road 4 tire. To wit: “The Michelin Pilot Road 3 was the first [motorcycle] tyre with sipes.” To think that I’d been using the word since before the PR3 was introduced.
So, there I was, smack dab in the middle of a professional existential crisis, while trying to pay attention to the presentation of an important, new motorcycle sport-touring tire. Clearly, I needed to focus to understand more and wait until later to do the research required to salve my damaged ego.
In the last two years, Michelin has been busy revamping its entire model line. In 2012, the Michelin Power Slick and Power Cup were introduced along with the Commander II cruiser tire. Michelin’s racing line was updated in 2013 with the Power SuperSport, while the street line gained the Pilot Power 3, the Pilot Street Radial, and the dual-sport Anakee III.
The Pilot Road 4 should be viewed as an incremental refinement of the technologies utilized in the Pilot Road 3 rather than as a whole-cloth new product. The PR4 line consists of three variations: the Pilot Road 4, the Pilot Road 4 GT, and the seemingly contradictory Pilot Road 4 Trail. These tire models break down into riders who want sporty performance but sport-touring tire wear on bikes 600cc and above, sport-touring tires for large sport touring models (such as the BMW R1200RT and the Yamaha FJR1300ES), or a street-going tire for adventure tourers who are honest enough to admit they desire the maximum street performance they can get out of their bikes since they will rarely be taking them off road. While all three models share the underlying technology, this review will focus on both the Pilot Road 4 and the GT (which differ only in the weight of the bikes they are designed to carry) with the riding impressions being from the GT through the lens of a 2014 Yamaha FJR1300ES.
Tires, Like Ogres, Have Layers
One of the characteristics unique to Michelin’s Pilot Road series of tires is the construction of its casing which combines techniques used in bias-ply tires and radials. Since sport-tourers tend to be heavy, the load-carrying ability of bias tires would seem to be ideal until you consider that they are often ridden at high speeds where a radial’s flexible sidewall and the associated larger contact patch at full lean are desirable.
So, Michelin developed its Dual Angle Technology (2AT). The first ply crosses over the tire at almost 90 degrees to the road while the second ply’s cords cross the tire (and therefore the first’s plies) at a different angle similar to a bias tire. Those plies are then supported by a belt ply with the cords following the angle of rotation as with a radial tire. These plies deliver a stiffer, better-performing tire with less rotational mass, thanks to the one less ply than the PR3’s construction.
Throughout the presentation, Michelin kept stressing three key features of the PR4: a 17% decrease in braking distance (as certified by DEKRA, an independent testing company), a 20% increase in longevity (similarly verified), and a 90° temperature range performance envelope.
The durability is largely addressed by Michelin’s 2CT dual-compound technology. The PR4 uses a total of three different rubber compounds, though only two at a time on each tire. The rear receives the hardest compound on its center 20% of surface to reduce wear in the straight up and down that street bikes spend most of their time. The remaining 40% on each side gets the medium compound for better grip. The front tire is similarly constructed with the center 40% receiving the medium compound with the remaining 60% dividing the soft compound between the two sides.
Wet-weather handling is addressed by the aforementioned sipes and grooves. This is where the technology gets really interesting. We’re all aware how grooves in a tire’s tread (and here I’m referring to the large grooves, not the narrow cuts) give space for water to be pushed away so that more of the rubber can contact the road. Circular cutouts in the tread create cavities to temporarily store water as the tire contacts the road. The “grooving ratio” of the tread block versus grooves varies by the amount that the bike is leaned over. Twenty percent of the center portion of the front tire (16% for the rear) is grooving. As the bike leans, the percentage changes to 14% front while remaining the same 16% on the rear. At maximum lean, which would only be reached in dry conditions, the percentage drops to 10% front and 7% rear to give the most grip possible.
The PR4’s sipes – and by sipes I’m using Michelin’s definition of thin, cut-like structures in the tread surface – perform the similar task but in a completely different way. The 15-degree angle of each sipe assists the leading edge of the sipe in cutting through the surface of the water and making contact with the road surface. Finally, the silica-impregnated polymer in the rubber compound aids grip in the cool road conditions associated with wet riding.
Getting Down to Business
For the hands-on portion of the Pilot Road 4’s introduction, the Michelin folks had a ride that would allow us to sample the rubber in many of the conditions the tires were designed to handle. (Alas, there was no rain to test wet weather traction.) The fun portion of the demonstration began with the famed Angeles Crest Highway, then headed east through the Angeles National Forest and the San Bernardino National Forest before ending at Big Bear Lake north of San Bernardino. However, the initial hour of riding consisted of urban and freeway use required to get to the other side of Los Angeles. As we sweated our way through the belly of the beast in unseasonably warm spring weather, having a new product to focus on sounds like a great way to pass the time. Only here’s the rub: the PR4s were utterly unremarkable with nothing distinguishing them from the OE Bridgestone Battlax BT-023 tires in this setting.
While the Michelin PR staffers reading this text attempt to resist the urge to reach for the antacid, I’ll add this: Since the 2014 Yamaha FJR1300ES I chose to have the PR4s mounted on was already so well balanced in these conditions, the only way the Michelins could have become remarkable would have been to do something poorly. When riding in parking lots or on city streets or even on the freeway at the low speeds we were limited to by traffic, the PR4’s construction was so under-stressed as to practically yawn at the task. If some car jockey had done something requiring dramatic maneuvers, like swerving or panic stopping, I’d have some initial comments about how the tires worked. Instead, I can only say that were black, round, and held the appropriate amount of atmosphere as we bided our time through the concrete queue on our way to the mountain roller coaster.
Once at the mountains, the riding began in earnest. The PR4’s turn in is responsive – even on a big, heavy bike like the FJR – feeling a bit easier to turn than the OE Bridgestones. The front tire’s round profile allows the rider to dial in the amount of lean required for a corner. Additionally, the profile made mid-corner line changes easy with minimal effort. Again, the PR4s were a skosh easier to maneuver than the stock ‘Stones in this regard. Since a recent rain had left the roads quite dirty, with patches of sand from runoff and the rockfall that follows rain in California mountains, frequent – sometimes multiple in a single corner – line changes were required throughout the ride as various road hazards appeared around blind bends.
The ease with which the FJR’s amount of lean could be controlled made side-to-side transitions through linked turns even more fun than they usually are. The bike could be lifted up off of one side of the tire, flipped across the center line, and precisely stopped at the desired lean angle. Although initiating a direction change this dramatic required some muscle to start, the final positioning could be accomplished with minimal effort – all of which could be accomplished with slightly less effort with the stock tires.
Grip was exceptional throughout the day’s travel on a seemingly endless ribbon of undulating pavement. This is even more notable since, as I said before, the pavement was quite dirty in places. In fact, it was so dusty that I needed to close my helmet’s chin vent because I kept getting the sand, being kicked up by the other riders, in my eyes. Add to this equation the unpredictable gusting wind, sometimes in excess of 40 mph, that would frequently add abrupt loads to the tires’ contact patches mid-corner. Picture entering a corner with the wind blowing from one side of the bike only to have it switch directions and radically change in intensity before the exit, requiring immediate – sometimes sudden – steering inputs to hold the desired line. How the PR4s compared to the BT-023s in this regard, would be pure conjecture without a side-by-side comparison in the same conditions, but they both provide grip that would have been shocking for a sport-touring tire just a decade ago.
The PR4’s high-speed stability was also impressive. During one long descent, the canyon opened up for miles of straight road with occasional sweepers thrown in for good measure. At speeds faster than my lawyer says I should mention here, the FJR remained completely stable whether on the gas or off. Bending into the corners at this elevated speed did nothing to ruffle the bike’s composure. This was with a 170-lb. rider, his riding gear and two completely full saddlebags. How this compared to the OE tires, I honestly can’t say. My triple-digit experience of the Bridgestones was limited to short blasts straight up and down on the freeway which doesn’t really stress the tires. Similarly, I wish I’d had a chance to see how the PR4s felt with a passenger at elevated speeds, but undertaking these sorts of shenanigans with my wife on the back would probably land me in divorce court.
While I can’t put numbers on the Pilot Road 4’s braking ability, I can say the tires were completely stable under even the hardest braking – even at the cusp of ABS intervention. Applying the brakes mid-corner or trail braking at the entry did not cause the FJR to try to stand up or alter its line in any way. Instead, the contact patch gave enough feedback to allow the brakes to be carried well into a corner – all while maintaining completely neutral steering.
Finally, while I didn’t test the limits of the claimed 90-degree operational temperature range (23° F – 113° F), the PR4s warmed up quickly in 48-degree weather after sitting overnight in close to freezing ambient temperatures. Still, the tires were ready for cornering in short order, capable of reaching peg-grinding lean angles in just a few turns with nary a slip nor a squirm. Additionally, after two days and a couple hundred miles of twisting pavement, the Michelins looked barely scuffed in. This bodes well for the long-term durability of the tires, but we’ll have to wait until they’re shagged to make a definitive judgement.
After a few hundred miles, I can say that the Pilot Road 4 tires I sampled are a worthy replacement for the Pilot Road 3. In fact, the PR4s are so good that BMW chose them for OE fitment on its 2014 R1200 RT, meaning that they will be mounted on roughly 40% of the RTs sold. Still, the PR4s can’t really be a replacement if the PR3s are still available for sale. In fact, both the Pilot Road 2 and Pilot Road 3 tires are still available at a new, lower cost. If you’re happy with the generation of Pilot Roads currently on your bike, they’ll remain available.
The standard Michelin Pilot Road 4’s MSRP ranges from $224 – $229 for a front and $271 – $331 rear. The GT version bumps the MSRP to $238 – $241 and $296 – $344, front and rear, respectively. The PR4 Trails weigh in at $252 – $265 front and $306 – $315 rear.
If the Pilot Road 4s perform for the duration of the tires’ life the way they did over the past two days, the PR4s will be top-notch tires for the sport-touring rider or the daily rider who doesn’t want to sacrifice tire life for the sake of performance.