On The Street And At The Track With Falken Azenis RT615K Tires

falkentest-leadartHotchkis hosted an autocross event at Auto Club Dragway in Fontana, California, as part of the NMCA West event series. As you’re likely aware, Hotchkis specializes in designing suspension components for both vintage and modern musclecars that transform straight-line street machines into genuine corner carvers, so the event’s musclecar-focused theme seemed like the perfect venue to head out to with Project Blank Slate – our Trans Am-series inspired, 502ci ’69 Chevrolet Camaro – for its first shakedown runs in order to put the Falken Azenis RT615K tires on the car through their paces.

Origin Of The Species


Falken may have been an unknown commodity in the U.S. a decade ago, but their strong research and development focus on motorsport in recent years has made the brand synonymous with high performance.

The RT615K is the latest in the evolution of Falken’s tires that are designed specifically for high-performance enthusiast drivers who use their cars for track duty and live in dry climates – the tire’s DOT legality means track rats can head out to the race course and compete once they’ve arrived without having to swap wheels and tires.

The RT615K’s 200 tread wear rating means it is also a popular option for Street Stock (or equivalent) classes in SCCA, NASA and car club events, as well as the ChumpCar endurance racing series and most classes in autocross events where pro touring-style cars like our Camaro would be slotted.

When pro touring builds started gaining in popularity a little under a decade ago, builders were largely locked into domestic tire brands if they wanted to get some competition-caliber rubber on the car, and here in the U.S., Falken was a virtually unknown brand at the time. Slowly but surely the word got around about the brand and their performance tires, and racers discovered that Falken’s offerings were outperforming brands that were, at the time, considered the industry standard.

One of the key benefits to a DOT-approved performance tire like the RT615K to those of us who live in warm, dry climates like southern California is that you can potentially use them all year, both around town and at the track, eliminating the need to bring an extra set of wheels and tires with you when you head out to a road course.

The lineage of the RT615K can be traced back many years ago to the introduction of the RT215, a model which similarly focused on catering to driving enthusiasts that participated in autocross and track days and wanted to drive their car to the track on the tires that they competed with.

The RT215 was later replaced with the first version of the RT615. With the expansion of Street Stock rules classes in SCCA, tire development escalated, with more tire brands getting involved and upping the ante for the industry as a whole. This sort of trend was great news for drivers, as the segment swelled to include numerous options for DOT-legal track day tires, like the BFG Rival, Bridgestone Potenza RE71R, Dunlop Direzza, and Hankook Ventus R-S3.

More Of Everything


The RT615K’s huge side shoulder blocks provide sharp initial turn-in and great lateral grip. The the solid center rib helps wheels that receive power to maintain grip, similar to drag radial designs.

As the successor to the RT615, the RT615K is said to offer even more responsive turn in, mid-corner stability, and the ability to get more aggressive on the throttle exiting corners. “The RT615k now sports more dry grip and handling without giving up the predictability or the wear characteristics of the previous version,” says James Yim, of Falken Tire. “This new compound improves grip, and extra care was also taken to handle the increased heat generation of track use.”

The RT615K boasts generous side shoulder blocks that are designed to help minimize understeering characteristics, while the drag radial-style solid center rib helps to mitigate wheel spin under power.

Of course, as we demonstrated in Fontana, there is still a threshold to that level of grip to be discovered, particularly in the rearend when the vehicle in question is dishing out as much power to the rear wheels as Project Blank Slate is, even with a tire as sticky as the RT615K.

As it turns out, nearly 600rwhp channeled through a close-ratio Tremec T56 manual gearbox can be a bit of a handful on the autocross course.

And while it isn’t much of a factor this time of year, Yim also points out that the RT615K was not created to handle low ambient temperature conditions for street use. “If the outside temperature is 45 degrees Fahrenheit or below, extra care should be taken until the tire reaches operating temperature range,” he cautioned. Something to keep in mind if you live in a particularly dry climate, like California, and are considering using a tire like the RT615K on a year-round basis.

The Car

For those unfamiliar with Project Blank Slate, suffice to say that this is a far cry from a stock first generation F-body.

Blank Slate packs some potent hardware that includes a fuel injected talldeck LS small-block, coilover suspension and Wilwood brakes front and rear, Evolution seats and a whole lot more. Read all about the build in the links below.

Aside from its fuel injected and dry sump’d LSX, this car has been built to be a serious track performer with a full Chris Alston Chassisworks’ front clip that includes VariShock coilover shocks and VariSprings, g-Machine subframe connectors, a beefier anti-roll bar, rack-and-pinion steering, g-Street directional vaned rotors, and a whole lot more. Out back, Blank Slate boasts a four-bar coilover rear end system, also from Chris Alston Chassisworks, and a massive set of Wilwood disc brakes grace all four corners.

Truth be told, with all that motor up front, Blank Slate is probably more ideally suited to road racing (as that was the original inspiration for the build) than it is to more technical, low-speed autocross courses, but there was little doubt that along with the Azenis RT615Ks, this car was going to going to be pretty quick no matter what the context.

The Event

One of the virtues of autocross is that it offers a fairly painless entry point into competitive performance driving. If you've got a license, a helmet and a car in good running condition, you're basically ready to go.

One of the virtues of autocross is that it offers a fairly painless entry point into competitive performance driving. If you’ve got a license, a helmet, and a car in good running condition, you’re basically ready to go.

Each NMCA WEST Hotchkis Autocross event features a handful of different classes to compete in so that every car and driver have a spot where their vehicle will be competitive:

  • Modern Muscle
  • Classic Muscle
  • Compact Car
  • Exhibition Class
  • Fastest Lap of the Day
  • Fastest Lady
  • Hotchkis Cup

Hotchkis keeps the autocross rules pretty simple – you can read through them here. But for those who really like to cut the wheat from the chaff, we’ve honed it down to these key talking points:

  • A maximum of 75 vehicles are allowed entry per event day.
  • Participants must use DOT-approved tires with a minimum of 180 tread wear.
  • No R compound or racing tires can be used for official timed runs.
  • Functional seat belts.
  • Proper brake pedal pressure and travel.
  • Sufficient throttle return spring and secured battery.
  • All lug nuts in place and tight.
  • Hubcaps are to be removed.
  • Valid driver’s license and proof of insurance.
  • Registered, street legal vehicle. No race cars.
  • All loose items must be removed from the vehicle.


Project Blank Slate is an example of one of the more hardcore builds you would come across at the autocross course. On the opposite end of the spectrum, you could compete in a bone-stock minivan if you wanted to, provided it passes tech inspection.

And of course the standard tech inspection for leaks and/or other mechanical issues is required to run as well, but that’s really all there is to it. If your car fits this criteria and you have a helmet and $70 for a one day entry (or $100 for an entire weekend), you’re ready to hit the course.

Out On The Track

Beyond the thrill and the competitive nature of the event, another virtue of autocrossing is shaking down your build to see what works and what could use some tweaking. This was the first time the car had ever been on track, and from the outset it was clear that the rear coilover system was worlds better than the OEM piece it replaced.

But in order for it to reach its true potential on an autocross course, it would require additional dialing in, as the system’s current, particularly stiff, configuration saw it eager to step out during mid-corner bumps and on-corner exit as well.

This is another area where dialing a car in for the tight, low-speed corners of the autocross course is a different approach than one would take for the fast corners and high speeds of typical road courses.

Armed with a clear understanding of Blank Slate's penchant for oversteer, we were able to clean up our runs substantially. While we were placed in the Exhibition Class because we were there as members of the media, our fastest time would have put us in the middle of the Classic Muscle class among 15 other competitors.

Nevertheless, with a patient right foot and an ounce of courage we managed to string together some respectable runs, due in no small part to the new compound in the Falken Azenis RT615K rubber which is particularly well-suited to autocross duty since the tires warm to optimal grip temperatures quickly. The general consensus is that 80 to 95 degrees seems to be the sweet spot for tire temperature and above 125 degrees the RT615Ks start to get greasy and lose grip.

Our fastest times would have put us in the middle of the pack in a field of 16 cars in the Classic Muscle class – not bad considering it’s the first time we’ve had Blank Slate at the track.

Combined with the ability to simply pack up and hit the road when the event is over rather than having to contend with another wheel and tire swap when you want to head home, the RT615K proved to be a worthwhile option for dry weather performance for those seeking a tire that can do it all while offering extremely high levels of DOT-legal grip. You can find more information about the Azenis or any other Falken tire at its website, or your local tire dealer.

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Bradley Iger

Lover of noisy cars, noisy music, and noisy bulldogs, Brad can often be found flogging something expensive along the twisting tarmac of the Angeles Forest.
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