Eyesore Racing enterprise doing a warp speed tire test of the Falken Azenis RT615-K

The typical new tire introduction goes like this: The new Pazoosy Jaberwoky XR 745 Ultra R Super Star uses triple-inverted diagonal ply Inconel belts and a directional, asymmetrical tread pattern to optimize wet and dry grip, minimize road noise, increase your fuel economy and magnify your sex appeal. The sad truth is that neither the author, nor the PR team that fed him that line of technospew has any idea what triple-inverted diagonal ply Inconel belts are or what they do. 

  Obligatory Tire shot
  Obligatory tire shot. Looks just like the old one...

That's what makes this tire review great. I have no idea what Falken did to change this tire. The new Azenis RT615-K is just as round and black as the Azenis RT615 it replaces. In fact, the tread pattern is the same, most of the sizes are the same, and really the only visual distinction is the little "K" on the sidewall.

I do know that I'm a fan of the old Falken Azenis RT615. It wasn't the grippiest tire on the market, and it wasn't the cheapest, but it seemed to occupy a happy balance of cheap enough and sticky enough to be on your daily driver, your track car, or your car that happens to be both. I've pulled 1.0g with Project Silvia on these tires, I've done 1500 mile road trips on these tires, and I've endurance raced on them.

We've been running the 615s on our LeMon for 11 very successful races, capturing 4 outright victories and more top 5 finishes than we can be bothered to keep track of. Even at that pace, our tiny 195/60-14s easily last through the 14 or so hours that make up almost every 24 Hours of LeMons and still have enough life left that the ones that aren't hopelessly flat spotted still have at least a track day's worth of hoonassery left in them. 

At this year's Going For Broken race at Thunderhill we stumbled into a unique tire testing opportunity. We had 6 used, but still very serivceable RT615s in remarkably good shape after running a full 14 hours at Infenion Raceway and winning the Sears Pointless race. We also had 4 new RT615-Ks. Same car, same track, and over 2 hours of racing on each to sort out the differences. 

3 wheel starship
Yea, you can feel it up there...
The scientists among you have already spotted the one massive variable in this test of opportunity. The old tires were, indeed, quite old, with a full race under their belts already. Sears point had been remarkably easy on the tires, though, and remember those 11 previous races we've done on the same kind of tire. We know exactly what the RT-615 feels like on our car, and these, though a little square, were still in good shape. At most, fresh RT-615s might have been one second faster.

So, finally, what's the difference? About 3 seconds (or 2, if you want to assume our old tires were 1 second off their peak), knocking our fastest lap of Thunderhill (counterclockwise, full track, without the turn-5 bypass) from a 2:16:somethingorother to a 2:13:andalittlebit.

The RT-615-K has more raw grip than the old RT-615, but more importantly, its much easier to drive. The limit behavior is more forgiving, with smoother breakaway and more grip at high slip angles that makes them easier to control at the limit and beyond. This breakaway character manifestes itself in some unexpected ways. 

The damping from our tired old stock Miata shocks actually felt better with the new tires. Softer sidewalls? I don't think so. The sudden breakaway of the old tires, coupled with the extra weight of an 80-lb starship on the roof of our car, caused some sudden roll inputs into the chassis on turns 14 and 15 (a tight, 180-degree combination with several curbs and rumble strips) that would send the car into the bump stops and set up a very unprofessional bouncing, porpoising corner exit. With the 615-K, the smoother limit behavior meant breakaway and recovery weren't violent enough to over-work the suspension. The result was smoother car that suddenly felt like the shocks weren't 17 year old. 

  Death Cab getting close...
  There's nothing like a menacing Volvo all up in your dilithium crystals to make your push a little harder...
Braking performance was also much better. Since we started running our Frankenmiata, we've complained that the brakes are too front-biased and lock easily. We almost never manage to wear one of the 615s all the way down before an accidental lockup makes the tire too square to keep using. During the 8 hours we've run the 615-K, we haven't made a single flat spot. Not only does the increased grip help braking distances, but that smooth limit behavior makes the brakes easier to modulate at the limit, so its easier to unlock a locked wheel before things go all square.
Finally, the new compound seems more heat resistant. During our "test" I got into a 90-minute battle with Spec Miata driver Dean Thomas in the Death Cab Ford-302-powered Volvo 240. I pushed the car hard for much longer than I normally would in a LeMons race, trying desperately to put some distance between myself and that giant Volvo bumper. Past experience suggests the same level of aggression would have overheated the old tires, causing them to go a little greasy. The 615-Ks held up to the flogging with no appreciable change in performance. 

In short, the new Azenis RT-615-K costs a few bucks more than the old RT-615. Its worth it.

Want to see the "test" in progress? Check out these videos:

From the Starship: (turn down the volume)


From the Volvo: (turn the volume back up)

More from the Volvo:


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Tuesday, May 25, 2010 7:13 PM
Good to hear the new 615K's are treating you well.

Having the Enterprise mounted on the roof of the Frankenmiata is just about the most awesome thing I've ever seen. Even my girlfriend likes it too :)
Tuesday, May 25, 2010 7:31 PM
Embarrased to admit I finally got my first set of the old style tires on my second B13 in 2009, the grip is impressive esp considering they are on the stock B14 SE-R wheels (narrower footprint). Kinda makes me look at the Kumho XS's and RE-11's and say, "so what"? I tracked my Kumho XS's last year and put almost 2000 miles on them, they seemed to not tolerate the heat of longer sessions, they were absolutely terrible in the wet (really, spun the car once with barely a twitch of the rear end).

If the new ones are close, sign me up - great all around tires that don't seem to give up much worth talking about when you need a tire that lasts and does everything pretty well.
OMG Its Weasel
OMG Its Weasellink
Tuesday, May 25, 2010 8:03 PM
I like the commentary in the Death Cab radio.

"dont hit each other"
":thumbs up:"

This looks like such great fun.
Bob Holmes
Bob Holmeslink
Wednesday, May 26, 2010 6:57 AM
Coleman, you are seriously warped!!
Thursday, May 27, 2010 1:00 AM
Can't help but notice that with the vent in the front, the saucer is shaped a little like an airfoil. Probably doesn't make any downforce, but it would still be the best wing ever.
Thursday, May 27, 2010 7:47 AM
Yeah, I was wondering if it made any downforce also. I love how well done the graphics are on the side, from the pictures, it looks amazing!

And Romulan, I'm sure you disagree, but the best wing ever for a car would have to be an X-Wing type wing... done similarly as here, but with 4 wings sticking out the sides of the vehicle and the rest of the X-Wing as a graphic on the car. Those should be easy to make into (down) force producing wings, though they might make overtaking maneuvers a little tricky.

Awesome tire review btw. =) Nothing beats driving a familiar car with only single change made, and then "testing" the snot out of it.
Thursday, May 27, 2010 8:10 AM
Is that Volvo using 1st gear? Is that because of some whacky combination of T-5 and Volvo gearing that results in a 55mph 1st gear or something?
Thursday, May 27, 2010 3:11 PM
I'd be interested in seeing how these stack up against the RA1 or R888.
Dave Coleman
Dave Colemanlink
Tuesday, June 01, 2010 7:24 AM
The RA1 and R888 are true R-compound tires. Far grippier than the RT615K, and far harder to get away with on a daily driver. I'd expect them to be a few seconds faster, but sadly, I can't really do that comparison test. LeMons rules limit you to tires with a treadwear rating of 190 or higher. The RT615K is 200, while the RA1 is 40!
Friday, June 04, 2010 6:52 AM
Have you had a chance to try the Direzza Star Specs? How do they compare?
Monday, June 25, 2012 1:36 PM
I love the Enterprise on top!
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