by Steve Atlas

Raising the Rubber Wall

It’s rare that a new tire comes around which really sets us back, that truly takes a big jump forward in performance – especially in the sporting world of two wheels.

Those rubber spinning rings we ride on have been on bikes from nearly the very beginning, thus tire development has been a century in the making. And with a market as stacked full of high-performance options as the sportbike world, making small gains is understandable; I mean, really, how much more grip can they squeeze out of those black and round doughnuts while still making them last on every-day roads? Thus, when Dunlop invited us out to Las Vegas to give their new Sportmax Q2 street/trackday tire a try, we weren’t exactly expecting a revolution. (The original Qualifier was already an awesome tire – how much better can the Q2 really be?)

[Hint] As it turns out, sometimes one gets more than they expect…

The Big D opted to release their new Sportmax Q2 rubber at Spring Mountain Motorsports Park, the exact same place we first tested the original Qualifier a few years back. And the first thing you notice is the tires’s warm-up time – or lack thereof. One can easily roll out of the pits and slam a knee on the ground right away.

Due its relatively low operating temperature and new rubber compounding, the Q2 allowed for instant confidence and impressive lean-angle straight off the bat. Although we wouldn’t recommend trying it quite this quickly, we were able to have a knee on the ground the very first corner out of the pits – all in the name of testing, right? And while it was over 90 degrees outside and SMMP provides more than ample grip, this was still quite impressive. Even when brand new they were easily scrubbed and up to temperature within a single lap.

Faster heat-up time? Check.

SMMP is the kind of track technical riders’ dream of. While lacking the elevation changes of a Barber Motorsports Park or the speed of Road America, the 2.2-mile Nevada road course is by no means easy. One is always working – turning, braking, accelerating – there are no long straights in which to rest. It’s for this very reason testing tires at SMMP is almost ideal. It’s also for this very reason it’s impossible not to notice how much better the tire’s outright adhesion is as one is continually exploring these limits.

In testing, Dunlop has shown the Q2 to be able to achieve over seven degrees more max lean angle as well as an additional 0.3g of sustained lateral grip. In the real world, this means being able to push a modern sportbike damn close to its limit with confidence like we’ve never seen in a road tire before. In fact, after riding the Q2 for a day I have a hard time even calling it a “road” tire. It easily has the outright grip of a DOT-approved race tire from a mere two or three years ago, and not far off that of Dunlop’s current race rubber. And not only does it have improved grip, but the grip feels much more mechanical, more human. You feel far more connected to the road in an analog kind of way as opposed to a detached digital feeling that some tires can give the rider.

This instant warming and improved grip is in part due to Dunlop’s MT (Multi-Tread) technology. Also seen on their Sportmax GP-A road race rubber, what this does is allow different areas of the tire to be made from different compounds of rubber so as to achieve the desired amount of life while also providing improved grip.

Longevity is achieved by running a harder section of rubber down the center of the tire, designed with stability, cooling and mileage as its primary focus. Grip comes from strips of a much softer compound rubber on each side, specifically designed to increase traction at medium to high levels of lean.

For those more techie folks, these sides of the tire are made from a high concentration of ultra-fine carbon black (UFCB) and their “special” proprietary resin, bonded together to create the compounds’ polymers and give the claimed added grip. The result of this is also a very dense and “tight” bond, which is what gives the fast warm-up time. Furthermore, a modified tread pattern makes for a bigger contact patch and greater “land to sea” ratio, the result of a lower percentage of grooved void areas. In Layman’s terms, the sides are a direct decedent of Dunlop’s Sportmax GP-A road race tires and as a result have far more grip. Enough said.

Improved grip? Check.

Pahrump’s long sweeping turn’s one and two flow from right to left, then exit down a short-shoot into a tight turn three. Due to the bike still being in transition from exiting the left-hand turn two and the amount of braking required for the right-hand turn three, it’s easy for a machine to get unsettled – especially at the pace we were pushing later in the day. Not an issue with the Q2.

Like the previous Qualifier, only better, the new Dunlop is planted and rock solid. Where the old tire had a bit of wiggle, or squish compared to race

rubber, the Q2 bridges that gap and features a more planted feeling carcass. Though it’s still a bit “street” feeling, there’s no question it’s more planted than the previous tire. This comes as the result of an updated carcass construction.

Up front it’s similar to that of the Qualifier it replaces, with a pair of nylon carcass plies and two aramid (another word for Kevlar) reinforcing belts making up the basic construction, both designed for stability. Where it differs is with the redesigned continuous hex beads that run along the sidewall, which are both lighter and stronger than the previous model, further stiffening up the tire.

As you can see, the name of the game these days is making the tires stiffer. Handling this task out back, due to the higher stresses from today’s big-power liter-bike is far more than ever before, is Dunlop’s JLB (Jointless Band) construction. This continuously wound JLB sits atop a newly designed aramid belt, derived from their GP-A race tire, giving said added stiffness as compared to the previous Qualifier.

Added stability? Check.

This same opening section of turns, as well as several other spots on the tight and technical SMMP, requires a bike which can turn quickly from side-to-side. Without it one would be in for a long and strenuous day, which is sometimes the case of street-bred rubber out in Pahrump. Due to the previously mentioned need for stability, making an aggressive carcass shape typically takes a back seat. And while the new tire is no knife-edged racing slick, Dunlop did make the Q2 rear tire slightly more aggressive than the original Qualifier.

Because of the previously mentioned improved stability, this allowed Dunlop to be more aggressive with the tire shape and still keep it within their safety parameters.They did this by pulling in the sides and raising the overall height, which not only speeds up steering some but also gives a larger contact patch when at lean.

As far as our impressions of this improvement, while we no doubt noticed the tire steers quickly for street rubber, it’s not light year’s better than the previous model. Though remember, the previous edition was no slouch, setting the benchmark for the industry when it came out, so to say the new tire is any amount better is a stout compliment. The larger contact patch, however, we did quickly take note of, as corner-exit drivability is vastly improved over the previous model. The Q2 took a beating from all sides – everything from a 650cc V-Twin to the latest 1000cc Superbikes – and easily withstood the pressure.

Quicker flickability and better drivability? Check and check.

Our final racetrack testing point, one which nearly every street-bred tire comes up short on, is life. And by life, I mean its ability to withstand track-temperatures for extended periods of time without overheating and getting greasy. Typically a street-based tire has anywhere from five to 15 minutes worth of abuse in them before boiling over and losing grip. Now, at the track as abrasive as SMMP on a 90-degree day, this time window would typically be even less. This is a byproduct of designing a street tire to run at a much lower operating temp than race rubber, which allows for faster heat-up times and much safer everyday riding, but causes the tire to overheat on the racetrack when pushed hard.

Much to our surprise, we were able to push the Dunlop for a solid 15 to 20 minutes before signs of overheating started to show. And even then, they weren’t nearly as drastic as some of the competition or the previous Qualifier. Even more impressive considering by day’s end it was well into the upper 90s temperature wise, which only slightly reduced its life. Let’s put it this way: I was spent and ready to pull in by the time the tire was, that’s for sure!

To put this in perspective and give to an example of how good the Q2’s overall racetrack ability is: This is the first and only street-bred tire I’ve ever used which I could safely and happily conduct a track-only shootout on – without question. In fact, there’s a good chance I will do exactly that for an upcoming test, as they not only have the grip needed but will last far longer than a race tire..

Longer racetrack life? (Yep, you guessed it) Check.

I’m continually amazed by how much grip, stability and control engineers are able to extract from the little rubber doughnuts we ride on while still making them strong enough for every-day street abuse. It’s utterly awesome to think of what they will be capable of in 10 or 20 years time – who knows; maybe we’ll need full-body sliders. But as for now, there’s no doubt Dunlop has set a new standard for street-based sportbike tires with the Sportmax Q2. The outright performance really is simply staggering! Maybe they should have just named it the Dunlop Sportmax Benchmark?