Common Tread

Dunlop sets out to create the ultimate track-day tire

May 14, 2018

Back in April, MotoAmerica held a pre-season test at Barber Motorsports Park in Birmingham. In amongst all the usual suspects, like Elias, Hayden, and Beaubier there was a cryptic entry for "Dunlop Test Bike." Whoever that guy was, he lapped within three seconds of the fastest Superbike times of the two-day test.

Taylor Knapp
Taylor Knapp put the final, emphatic stamp of approval on the new Q4 tires when he lapped Barber Motorsports Park within three seconds of the fastest pre-season MotoAmerica Motul Superbike times. Photo by Mark Gardiner.
The "Dunlop Test Bike" rider was actually Taylor Knapp, an ex-AMA Pro and MotoAmerica racer who recently joined Dunlop’s elite test and development staff. Since Knapp’s a Known Fast Guy, it wasn’t surprising to see him put in competitive lap times, even on a stock-ish Suzuki GSX-R1000. What did raise eyebrows was that he put up those times on a street-legal tire, without using tire warmers between sessions. Before long, news leaked out that Dunlop had been conducting one final check on the all-new Sportmax Q4 hypersports tire.

So even before Dunlop assembled a few journalists at Chuckwalla Valley Raceway to try ’em out, I knew one thing was certain: If a pro racer could put up competitive Superbike times on Q4s, they could handle anything I could throw at them. (The datalog from Knapp’s Barber ride showed him routinely leaning past 62 degrees. The only times I’ve ever recorded such an angle, I was completely horizontal a moment later, if not tumbling!)

Dunlop’s Sportmax Q4 is not a replacement for the current Q3+ tires. Rather, it’s a stickier and more track-focused option that gives Dunlop a tire to rival Pirelli’s stickiest Supercorsa. It’s all-American product, conceived in Dunlop’s Buffalo, N.Y. plant, where it’s manufactured on the same equipment used to make MotoAmerica race-spec tires.

Dunlop Q4
The new Dunlop Q4. Photo by Brian J. Nelson.

How Dunlop Q4s were developed

The lead engineer on the project was John Robinson, who studied engineering at the University of Buffalo. Robinson was a Ph.D. candidate there before dropping out to take a job at Milliken Research Associates — a low-profile but influential engineering consultancy that works for automotive and racing clients. That was an incredible gig for a young engineer, but he was more passionate about bikes than cars, so when a position opened up at Dunlop, he jumped.

John spent a year in the factory, getting up to speed on motorcycle tire manufacturing in general and Dunlop’s proprietary "jointless tread" manufacturing technique in particular. Then, he spent two years as a race tech in the MotoAmerica series. About a year and a half ago, Dunlop’s product planners decided they needed a maximum-grip tire for track-day enthusiasts.

John Robinson
The new Q4 was John Robinson’s first complete tire line. He’s set a pretty high bar for himself. Photo by Mark Gardiner.

The new Q4 family was Robinson’s first complete line of tires. His goal was a tire guy’s Holy Grail: something with the grip of a race tire, that didn’t need warmers, could withstand numerous heat cycles and would last at least a couple of weekends.

Dunlop was happy with the carcass performance of the Q3 family, so Robinson stuck to similar (but not strictly identical) carcass designs. Front tires have two Kevlar belts, rears are single-ply. Both have carbon fiber-reinforced sidewalls.

Dunlop Q4
The marketing guys put this snazzy, on-tread branding on the tire’s "chicken strips." Photo by Mark Gardiner.
Robinson worked with Dunlop’s chief scientist to choose a few initial compounds to try. Since they wanted a tire that would grip well without requiring warmers, they stuck to compounds with relatively low glass-transition temperatures. "GTT," as tire guys call it, is the temperature at which the compound becomes brittle instead of rubbery. In general, it’s a good predictor of grip, and race slicks have GTTs as high as 15 degrees Celsius (59 degrees F). That’s no good for a tire that will be used without warmers, so their challenge was to cook up a compound that gripped well in spite of its relatively low GTT.

Dunlop Q4
The Q4s were sticky enough that even I could obliterate the branding. Photo by Mark Gardiner.
Dunlop’s facility in Buffalo allows for rapid prototyping. The machines that apply that jointless tread onto rear tire carcasses are basically three-d printers for rubber. That made it relatively easy for John to begin producing usable prototypes in those initial compounds, with hand-cut grooves.

Although Dunlop has a lab, and finite-element analysis capability, in house in Buffalo, what matters is how tires work on pavement, not on paper. The first stop for most prototypes is Dunlop’s own proving ground in Huntsville, Alabama. The new Q4s were also tested at Roebling Road, a track with aggressive pavement that’s great for wear testing; at Virginia International Raceway, which is a good place to learn how they handle being weighted and unweighted by elevation changes; and at Chuckwalla, which has reliably good winter weather. Although it was not mentioned in the press kit, I think they also did a quick run at New York Safety Track as well, to confirm the performance on cold asphalt.

Robinson got part-way through the process before hitting a dead end. One of those initial compounds worked very well on the first few tracks where they tested it, but only OK on some surfaces. He went back to the witch’s cauldron and added some eye of newt, and found a rubber that worked well everywhere.

OK, that’s not exactly what he did. The precise ingredients of the compound are confidential information. What we know is that the Q4 is a single-compound tire (unlike the Q3+, which has a silicon-infused center tread for improved wear and wet performance.)

Like all modern performance tires, Q4s are made of synthetic rubber (natural rubber is still used in high-mileage tires like the ones on heavy trucks). The Q4 compound is a blend of about 15 ingredients: various polymers, oils, carbon black, sulfur, then the proprietary newt eyes, bat wings, etc.

Dunlop Q4 at Chuckwalla
Although Dunlop’s testers look mainly at lap times, they fill out a form assessing about 10 aspects of each tire’s performance. One factor they look at is turn initiation. Does the tire respond predictably to steering input? Is it easy to turn? Answers: Yes, very. Photo by Brian J. Nelson.

The tread for front tires is extruded as a long flat belt, that’s cut and molded onto a carcass with carbon fiber-reinforced sidewalls and two Kevlar belts. The tread for the rears is extruded like toothpaste in a long spiral right onto a single-ply nylon carcass, which also has carbon fiber-reinforced sidewalls. That JLT machine allows Dunlop to control the thickness of the tread layer with precision.

No matter how the tread layer is applied, those "green" tires then go into heated steel molds where the carcass and tread are pressed into the mold surface in much the same way that a finished tire is inflated. That’s the stage at which the tread pattern is molded in. (It’s a common misconception that those little nipples on new tires are left over after rubber’s injected into the molds. That’s not true; they’re just expansion spaces to ensure consistent mold contact.)

During a small presentation the night before our test ride, Dunlop showed us a graph with their own proprietary "grip" factor on the X-axis and temperature along the Y-axis. The Q4 offered better grip than the Q3+ at all temperatures and even better grip than the slicks used in MotoAmerica at temperatures below 70 degrees Celsius (158 degrees F).

Dunlop Q4 test at Chuckwalla
The off-camber entry to Chuckwalla’s turn nine is definitely a place where you have to trust your tires. Photo by Brian J. Nelson.

Enough theory; let's hit the track

The next morning, we grabbed a breakfast sandwich at 6 a.m. and loaded into vans for the drive from Palm Springs to Chuckwalla. The goal was to be on track early, because by noon it was expected to be hot and windy. As per usual at a tire launch, Dunlop had assembled a cross section of modern sport bikes: Yamaha YZF-R1 and R6, Suzuki GSX-R600 and 1000, and a few Kawasaki ZX-6Rs.

Since I’d never ridden at Chuckwalla, I limited myself to one bike in order to minimize the number of variables I had to deal with. I chose the Kawasaki because a) the older 636 Kawis always seemed pretty user-friendly to me, back when I regularly did this stuff; and b) it was the only bike left after all the other journos skeedaddled onto the track.

I rolled through a couple of sighting laps, and was grateful that Dunlop had laid out cones marking corner apex targets. Then, per prior arrangement, I did a couple more laps behind Knapp, who’s put in hundreds of laps there in testing.

In general, Chuckwalla Valley Raceway is a pretty easy track to get a handle on, but I was acutely aware that I was the only newcomer to the track — to say nothing of the fact that after a long Kansas City winter I was so rusty that Dunlop should have made all the other riders update their tetanus shots before sharing the track with me. I have to say, knowing I was on tires that Taylor Knapp could push to MotoAmerica speeds gave me a lot of confidence.

CVR is not overly technical, but there are a few places, such as the double-left of turns six and seven, where you have to tighten your line in the middle of what amounts to one long, decreasing-radius turn. That’s a perfect example of a place where a little extra confidence was nice.

One of the only significant elevation changes is the turn eight-nine-10 right-left-right sequence over a small hill marked by a corner worker’s shelter. The left turn in that grouping is sharply off-camber, making it another place where you really have to trust your tires. Every time I went through there I repeated a little mantra that went, “Taylor Knapp used these tires at Superbike speed, Taylor Knapp used these tires at Superbike speed!”

Hey, whatever works.

Dunlop Q4 at Chuckwalla
The off-camber turn nine is followed by a downhill transition into Turn 10. It’s like a baby (much-less-scary) version of Road Atlanta’s famous Gravity Cavity. Still, at speed it’s a place that would put extra stress on the carcass of the tire. Photo by Brian J. Nelson.

When I asked Knapp what he liked best about the Q4s, he told me it was their ability to grab the pavement while still leaned over and really fire a powerful bike out of corners. CVR is more flowing than stop-and-go, but turn 13 is a long, long banked 180-degree right-hander where, as I was just learning the layout, I often found myself entering too slowly and accelerating all the way through. The rear always felt really hooked up in those situations.

In the same way there’s few real tests of acceleration, there’s also not many really hard braking zones. The only times I really "tested" braking stability were moments when I felt I was approaching a corner a little hot and braked harder and later. (But, I’ll note that stability under hard braking is historically a Dunlop strong point.)

To my way of thinking, turn initiation and mid-corner stability were perfect, as were side-to-side transitions. It’s been a while since I’ve ridden on hot racing slicks, but that’s the way I remember them feeling.

There are a few bumps at CVR, but none to speak of compared to northern-tier tracks where the ground freezes and thaws every year. So I wasn’t able to determine the Q4’s performance on bumpy surfaces. Bumps have always been Dunlop’s Achilles heel. The company has always preferred stiff carcasses that are stable under hard braking, at maximum lean, and under hard acceleration, even at the price of some instability over bumps. Dunlop’s marketing boss Mike Manning openly acknowledged that people who prefer other brands often do so because of the way competitors’ tires feel on rough pavement.

Manning also told me that in testing, Knapp once did two full days at Chuckwalla, putting more than 100 laps on one set of Q4s — and that was riding an R1 with a full Graves exhaust. “Not a bike that’s lacking in torque,” he added, unnecessarily.

Almost any track-day rider should get several days out of the new Q4s, if not more. That’s incredible wear for tires with grip levels (and lap times) comparable to slicks.

When I suggested to John Robinson that his Q4s would be a better choice for most club racers than actual race tires, he explained that he’d been careful to design the Q4 with less than a 95:5 percent land:sea ratio, and made sure the slick shoulder was less than 35 mm wide. So, it’s race-legal in most classes that require treaded tires.

“For a club racer who comes to the track and unloads his trailer alone, and doesn’t want to mess with tire warmers and getting his bike on and off stands, it’s a tire that offers the performance of a slick after about half a lap of warm up, and which would last most racers more than an entire weekend,” Robinson told me. Then he smiled enigmatically and added, “I can’t give you any more details right now, but we have some plans to demonstrate that.”

My guess is that later this summer, Taylor Knapp’s going to show up at a few races to prove just how fast it’s possible to go on a street-legal tire sans tire warmers.

I would have loved to take advantage of the open track even longer but none of us could handle the heat past noon. Over a catered BBQ lunch, the consensus among the assembled testers was very positive. While everyone was dazzled by the Q4’s grip, I was impressed by how user-friendly they were, too; sticky even when cold, long-wearing, always predictable on turn-in and in transition.

I have no reservations about recommending the Q4 for any track-day rider. It would also be worth trying a set if you’re a club racer who can’t be bothered with the hassle of tire warmers, or can’t really afford the expense of mounting fresh tires between Saturday and Sunday sessions. When it comes to aggressive dry-weather sport riding on public roads, I’m certain they offer extraordinary grip but cannot attest to how they might handle bumpy sections. If you try them in that setting, please let me know how they stack up, by leaving a comment.

Kawasaki ZX-6R on Dunlop Q4 tires at Chuckwalla
The Q4 is available in several rear sizes, including some with taller aspect ratios to provide sharper handling characteristics and an even larger footprint near maximum lean. Though I stuck with the Kawasaki ZX-6R all morning to minimize the variables, I did try a similar bike with the taller 180/60ZR17 rear tire for one short session. I think I liked that tire even more. Photo by Brian J. Nelson.

Dunlop is already shipping new Q4s. Available sizes and MSRPs are listed below, but Dunlop doesn’t pressure retailers to stick to those prices and RevZilla is selling Q4s for 30 percent off MSRP. The range of sizes (wider than the Q3+) means riders can choose Dunlops for bikes, like the Ducati Panigale, that are equipped with traction-control systems that compare wheel speeds at the front and rear and need very particular tire circumferences.

Dunlop Q4 available sizes

  • Front
    • 120/70ZR17 MSRP $201.27
  • Rear
    • 180/55ZR17 MSRP $258.78
    • 180/60ZR17 MSRP $264.51
    • 190/50ZR17 MSRP $294.42
    • 190/55ZR17 MSRP $302.17
    • 200/55ZR17 MSRP $358.86