It would be interesting to see consistency calculated in the lap time tables to see if that's changed any, or just if the driver seems to be getting more dialed in over the day.
Photograph by Timothy Harper
Things move quickly in the high-performance tire world courtesy of constant innovations in materials, design and manufacturing techniques. Getting an optimal combination that hits all of the possible design goals takes a huge investment of both time and money. And if the tread pattern is also new, you’ll need a bevy of shiny new molds–another large expense.
Given that the UHP replacement tire market is small compared to that of the average grocery-getting people mover, change comes slowly within any particular brand. Lower return on development resource investment means product cycles typically last six years at a minimum.
That’s why tiremakers often make running changes, extending the lifespan of a particular model by addressing any shortcomings that show up through real-world use. It might be a tweak to the compound for better grip or longer wear. Perhaps it’s a crisper steering response through a construction change. Or maybe inconsistencies in manufacturing need tightening up.
Sometimes these changes are done covertly, with no notification to the customer base. Other times, it’s deemed important to market the changes as new.
Falken has used this methodology for many years in its motorsports-oriented offerings. The venerable Azenis RT615 has gone through several iterations in its 20-year history, including the RT615K and then the RT615K+, the latter still a popular choice for budget performance use.
The Azenis RT660, the follow-up model line, was first introduced in 2020, taking the market by storm just as Bridgestone exited by halting production of the popular Potenza RE-71R. Delivering similar performance to the front-running Bridgestone, the Falken was less expensive and came in more fat-boy sizes coveted by enthusiasts. Falken scooped up market share in record time.
Pointy-end status lasted a solid three years until Bridgestone responded with the RE-71RS, a tire that was a bit quicker than the Falken in the dry and lots faster in the wet. Further, reports of unusual RT660 wear began to surface alongside performance deficiencies linked to certain production batches. And finally, many users reported tires heat-cycling out long before the tread wore out. None of these paper cuts was a major deal-killer by itself, but Falken was keen to address all of them.
Enter the Falken Azenis RT660+.
From left to right: Bridgestone Potenza RE-71RS, Falken Azenis RT660+, Falken Azenis RT660. Photograph by Andy Hollis
Responding to its customers, Falken implemented tighter manufacturing tolerances to address tread splice issues, durability and batch-to-batch consistency. A change in the cap ply–one fewer nylon belt–created a larger contact patch with more uniform pressure distribution for better cornering and heat management.
As a result, the new tire is quicker, more consistent and longer lasting. These changes also result in some weight savings–7.5% for our test size. The cherry on top? Five new 20-inch sizes are now on offer.
How much better is the new version? Falken sent us a set of both the outgoing and incoming models to compare. To complete the test suite, we added a set of the Bridgestone Potenza RE-71RS as our benchmark–this particular set a veteran of two previous tests, now worn to a 6/32 tread depth. All of our 245/40R17-sized test tires were mounted on 17x9-inch 6UL wheels by 949 Racing.
Before driving them in anger, our fresh Falkens were treated to an initial heat cycle with six laps of ever-increasing intensity at the track, bookended by a highway drive from our home base. This process helps cure the rubber, realigning the molecules for stronger bonds. Durability and consistency are typically improved. In particular, we’ve seen RT660s with accelerated center rib wear when not given a proper initial cycle.
Test day at Harris Hill Raceway in Austin, Texas, dawned mild with overcast skies and temps ranging from 68° to 72° throughout the morning. Without the typical sunbaked track surface, these conditions were ideal for maintaining consistency within each session.
We first mounted up a set of older scrubs and spent a solid half-hour cleaning the track and dialing in our driving–the track had not seen use by cars for almost a week. Once lap times stabilized, we bolted on the first set of test tires and set to work.
We love this tire’s versatility. It’s quick in both the wet and the dry with excellent driving feel. Our only beefs are vagueness at the limit and a tendency to heat soak fairly quickly at full tread. Both of these traits diminish once tread reaches the halfway point.
A hard out lap turned on the compound quickly, delivering three strong laps at the limit before heat soak reduced the pace a bit. Once the tire was soaked, careful attention to staying just under the limit was necessary for more consistent pace.
We’ve tested this tire a number of times over the years, and it always impresses. While its pace is not quite up with the current pointy-end tires, it is very easy to drive at or slightly over the limit. With a clearly defined edge to its grip and a quick recovery, the tire can be danced around for a very satisfying experience.
The RT660 came up to pace quickly during the out lap, delivering a series of consistent times about eight-tenths off the Bridgestone’s best early circuits. Despite pushing hard, the feel on the final lap was the same as the first. Consistency and accessibility are hallmarks of this model.
The updated Falken performs a little better than the original in almost every way. While mid-corner grip hasn’t changed much, every transitional phase is better defined. Full gas to full brake, trailing into the corner and powering out on exit–each was more controlled and predictable.
All this while maintaining excellent consistency and heat tolerance due to an unchanged compound. It’s a delightful combination that will match well with the driving style of many.
With the track being so green from five previous consecutive days of motorcycle-only use, we were a little nervous when we bolted the Bridgestones back on to bracket our test. Was the Falken’s lap time improvement merely the track cleaning up? Our fears were allayed as we lapped on average within a tenth of our earlier session. Satisfied with our comparison data, we packed up.
One key feature of the RT660+ update is the ability to brake later, especially under trailing conditions, yet still hit the apex. In this comparison of the speed traces between the two tires, notice how the cumulative time delta line bumps up during each braking event.
Five years is an eternity in the fast-paced 200tw market segment, and Falken was smart to tweak its design to extract a bit more performance. The RT660+ is still not quite as quick on single-lap pace as the front-runners, but it can turn those times easily and consistently. This makes it an excellent track day tire and also a good choice for endurance racing, where it should last for the typical 8-hour race.
It’s also a wise selection for classes with spec tires, such as SCCA’s Solo Spec Coupe and Gridlife’s Club TR and Sundae Cup, as the newest Falken is consistent, durable and fun to drive–often the perfect tool for the job.
It would be interesting to see consistency calculated in the lap time tables to see if that's changed any, or just if the driver seems to be getting more dialed in over the day.
Lap times are not the issue with the Falken, its the center rub falling off after 3 laps. If that didn't happen, they are an improvement over the old. They burned me twice with poor quality, it will take more data to convince me to try them again.
theruleslawyer said:It would be interesting to see consistency calculated in the lap time tables to see if that's changed any, or just if the driver seems to be getting more dialed in over the day.
That's the whole point of bracketing the test. Same tires are run at the beginning and end. Gives a read on any changes related to driver or surface change.
For this test, the final set of runs on the RE71RS are about .15 quicker on both single lap best and average (not shown, but I've done the math). So a case could be made that a small portion of the 4 tenths gain from RT660 to RT660+ was due to that. But single tenths are also easily within the noise of this type of testing.
Further, we are privvy to some other unpublished real world 3rd party comparison testing of these two tires from a reliable source. And those results are similar to ours, both the objective and subjective portions. So our confidence is high on this one.
pinchvalve (Forum Supporter) said:Lap times are not the issue with the Falken, its the center rub falling off after 3 laps. If that didn't happen, they are an improvement over the old. They burned me twice with poor quality, it will take more data to convince me to try them again.
Did you do a mild initial heat cycle (or pay to have it done) before hammering on them?
I've seen this happen with RT660's that were bolted on as stickers and pushed hard.
Either way, one of the results of the change was more even pressure distribution across the face, so that should help the cause.
Andy: Did the 660+ develop a tread splice failure? Looks like something in the photo.
Also, funny typo "Flaken" in the photo caption!
jwasilko said:Andy: Did the 660+ develop a tread splice failure? Looks like something in the photo.
Also, funny typo "Flaken" in the photo caption!
Good eye!
Actually, I must have those labeled backwards -- it was the outgoing tire that did that. Pretty ironic.
I'll have the guys get the piece fixed up. This one got rammed through quickly.
....
Ninja edit now complete.
PS: Failure is too strong a word. It's cosmetic only and typically wears away in short order.
If memory serves me well, the RT660s got faster after losing 2/32nds of treadwear. Would be interested to see a test of these versus RE71Rs at a similar tread depth - I recall the RE71RS being a bit squirmy at full tread.
Andy Hollis said:theruleslawyer said:It would be interesting to see consistency calculated in the lap time tables to see if that's changed any, or just if the driver seems to be getting more dialed in over the day.
That's the whole point of bracketing the test. Same tires are run at the beginning and end. Gives a read on any changes related to driver or surface change.
For this test, the final set of runs on the RE71RS are about .15 quicker on both single lap best and average (not shown, but I've done the math). So a case could be made that a small portion of the 4 tenths gain from RT660 to RT660+ was due to that. But single tenths are also easily within the noise of this type of testing.
Further, we are privvy to some other unpublished real world 3rd party comparison testing of these two tires from a reliable source. And those results are similar to ours, both the objective and subjective portions. So our confidence is high on this one.
Yah, I understand the bracketing. However my catalyst pumps out a consistency stat. It would show how stable the lap times are. Sometimes you talk about tires falling off, or maybe that one tire is easier to drive than another. That sort of data could probably be quantified by looking at how variable lap times are. I was just looking at all the lap times and trying to figure it out in my head.
In reply to sibanez :
RT660 long-term study right here ==> https://grassrootsmotorsports.com/articles/how-optimize-tires-quicker-laps-and-longer-life/
As for the RE71RS, here's a test with both a full tread and 5/32 version -- big difference ==> https://grassrootsmotorsports.com/articles/hoosier-trackattack-pro-tire-test/
And finally, we have another long-term test result we'll be sharing soon, along with lots of other 200tw tips & tricks.
In reply to Andy Hollis :
Serious ninja editing!
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