Street Tire Comparison

[Kestrel]

This review of street tires is a little old (Dec 2005), but compares most of the tires that enthusists (like us!) seem to buy. Interesting to see where the hallowed Kumho Ecsta MX wound up.

http://www.caranddriver.com/reviews/hot_lists/high_performance/features_classic_cars/tire_test_the_quick_and_the_tread_feature/(page)/1


Two disclaimers:

• This is a Car and Driver review...
• Sorry if this is a "re-post" or old news -- I just ran across it!

[Darron65]

They didn't test Falken Azenis!!

[CosmosMpower]

Wow that is pretty old and doesn't include many of the new street tires like the RE-01R, R1R, Direzza Z1 etc. Interesting that the AD07 has been around 3 years though and still very competitive.

[ken o]

I like the test Grassroots Motorsports does.

The Best of Both Worlds

As Street Tires Keep Getting Stronger and Faster, We Test the Current Crop

story by Per Schroeder

Who doesn't like the idea of a dual-purpose tire? You know what we're talking about: that vulcanized Holy Grail, the do-all and be-all tire that allows you to run with the big dogs during Sunday's track session, then roll silently on the way to work the next day come rain or shine? It's a great concept, since many enthusiasts would prefer to have one tire that can do it all - or at least do it all well enough - rather than deal with logistical and financial challenges of having a second set of mounted wheels for competition use.

Fortunately for many of us, this is no longer a pipe dream. The latest crop of ultra high performance tires has progressed to the point where they can be counted on to deliver mile upon mile of trouble-free use, while still acting as worthy companions on the track or autocross course. It's a win-win situation.

Although the general level of performance among today's high-end street tires is excellent, some brands will, inevitably, be faster than others. And since we're all about going faster, it's time for - you guessed it - a tire test.

For this comparison we've sampled some of the top tires in the enthusiast marketplace: Yokohama's Advan Neova AD07, Federal's 595RS, Bridgestone's Potenza RE-01R, and Falken's Azenis RT-615.

Let's Run 'Em

We ordered a set of each tire in the popular 235/40R17 size to fit our trusty 2005 Saab 9-2X test vehicle. The Saab was chosen as a test mule because it has proved to be stone-cold reliable, and with a few suspension tweaks can hang with our purpose-built STS Civic project on the track. (The Saab 9-2X is simply a badge-engineered Subaru Impreza, which makes our data especially relevant for your friends with WRXs and STIs.)

We mounted all the tires on identical Rota SDR wheels, which weigh a respectable 17 pounds apiece in the designated 17x7.5-inch size. They also look very good on our wagon. Mounting services were handled by Orlando & Sons, our local full-service gas station that happens to have some of the best mounting and balancing equipment in the area - as well as people who know how to use it.

Once mounted, all of the tires were driven approximately 100 miles on the street in various conditions, both wet and dry. They were then taken through a complete heat cycle, with each tire seeing several vigorous laps before being removed and allowed to cool. This pre-testing procedure did two things: It showed us how each tire worked in daily-driver use, and it completely removed the mold release compounds. The tires were tested at full tread depth.

For the timed portion of our testing, we used two different variations of the Ocala Gran Prix kart track. First we timed each tire over five continuous laps on the full open track, which allowed us to see how they would do in an HPDE open-track format. (The Ocala Gran Prix course can be hard on tires and quickly builds temperatures, even on cool days.) We ranked the open track performance based on each tire's average time.

The rubber was allowed to cool off as we set up the autocross course. We created an 18-pace, six-cone slalom on the track's main straight, using the pit-out entrance as both our starting gate and finish line. We then made five autocross runs on each tire, giving each set ample time to cool off between runs. (A blast of cool water was often used to help hasten this process, as the tires' pressures were adjusted to keep them in their happy range based on driver feedback.) The autocross portion was ranked by the tire's fastest lap.

To make sure that conditions had not changed substantially from the beginning of our testing process to the end, the Yokohama Neova was used as our control tire. We ran it first then again at the end of the sequence, and found no significant changes.

One nice thing about being based in Florida is that we can test tires year-round, so while our readers in the upper latitudes were shoveling snow, we were burning through tires with stopwatches running. The weather for our late-January test day was sunny, and just a touch brisk at 55 degrees. (Hey, we have to have something to compensate for the hurricanes and tornadoes.)


What We Found

Yokohama Advan Neova:

Welcome Back, Yokohama

Back in the day, all the cool kids ran Yokohamas. During the '80s and into the first part of the '90s, the company's flagship AVS Intermediate tire was an ultra high performance street tire that could handle itself well on the track. It worked on Porsches as well as Rabbits.

Yokohama replaced the AVS Intermediate with a succession of seemingly less aggressive flagship tires, and enthusiasts went looking elsewhere. The new Advan Neova AD07 brings Yokohama back to their roots.

On the street, the Advan Neova is a strong performer, offering plenty of grip before things get anti-social. The feel is actually very reminiscent of the original Yokohama R-compound tire, the A001R. The car corners on what feels like a firm, but still flexible, sidewall, one that allows some slip angle before the car breaks away. The slip angle can be managed at the limit with only a little bit of momentum loss.

Paradoxically, the Neova was quite good in the wet, especially for an adept track performance tire. We felt very little hydroplaning, even during a soaking Florida rainstorm. In the dry, some noise was evident at lower speeds, but it quickly went away past 40 mph.

Once you take it off the streets, the Yokohama offers a fast and consistent open track time. In our test, it posted the third-fastest mean and the second-quickest fast lap. There was no degradation in grip as the Neova warmed up over consecutive laps; if anything, it felt faster as the temperatures got hotter.

While a bobble on our fourth run (and a resulting cone) hurt the Yokohama's mean time, this tire's fastest autocross course was a mere four-thousandths behind the top time of our test.

The Advan Neova isn't inexpensive; the 235/40R17 size we tested goes for $202 a pop from our friends at The Tire Rack. However, this tire offers a great balance of wet and dry traction with few compromises. Those extra few dollars buy a well-engineered tire that is equally at home on the track or the street.


Federal 595RS:

A New Contender From Taiwan

The 595RS is the newest high-performance tire from Taiwan's Federal Tire. The company is expanding its line of grippy rubber to help build brand recognition here in the States, and the 595RS is touted as a maximum-performance tire that can deliver strong lap times. The 595RS is also said to exhibit easy breakaway characteristics, a handy feature for those in the drift scene.

The idea of performance tires from Taiwan may sound a little unusual, but many enthusiasts once said the same thing about Japanese- and Korean-made offerings. Nor is Federal the lone contender from that country: Maxxis is another Taiwanese company looking to make inroads in the American performance scene.

The street-driven portion of our test revealed that the Federal sounds a bit like the Goodyear Eagle F1 GS-D3, as it produces some hum at highway speeds. Like the Goodyear, the 595RS is also a fairly respectable performer in the wet.

When pushed to the limit, the Federal felt surprisingly like the Hankook Ventus R-S2 Z212, a tire we tested in our last street tire test. The 595RS has a lot of void area and quite a bit of flex in the sidewall, which made the tire feel pretty squishy and squirmy at the limit of adhesion - again, much like the Hankook. This trait equates to decent wet traction, but also results in a lot of sliding and a lag in transient response.

On the plus side, these issues can usually be reduced with tire shaving and pressure management. This tire also offers a broad slip angle that allows for a lot of sideways momentum before the car's speed is reduced.

Not only does the Federal share a lot of characteristics with the Hankook, but its lap times sound be similar as well: In our autocross testing, both the Federal and Hankook have consistently lagged a half-second behind the Falken on our 42-second course.

On the open track, it was a little hard to get the Federal to corner consistently, although its fastest lap was right down there with the Bridgestone and Yokohama. We're thinking that with a proper shave to 4/32-inch or less and some tire pressure and camber tuning, drivers will be able to make the Federal 595RS a contender. Its low price of approximately $125 per tire (online) in our tested size certainly sweetens the deal.


Bridgestone Potenza RE-01R:

Speed Meets Civility

Bridgestone is another company whose interest in our market has waxed and waned. Open a 15-year-old copy of Grassroots Motorsports, and you'll see many road racing cars carrying the Bridgestone logo. In recent years, they haven't done much in our world. Well, they're back.

The new Bridgestone Potenza RE-01R is a great tire with few, if any, downsides. As with the Yokohama, we noticed a slight "thrum" as the car decelerated to a stop and a bit of tread noise in the 30-35 mph range.

On track, the Bridgestone Potenza RE-01R was clearly the easiest to drive. It lacked the outright grip of the benchmark Falken at full tread, but had the easiest to modulate slip angle. It was very resistant to heat buildup, and we found our lap times were strong and consistent from start to finish.

The Bridgestone, like the Yokohama, would be a great choice for the enthusiast who likes to do both open track events and autocrosses with their daily driven car. Our bet is that this tire would outperform the Falkens as the ambient temperature increases.

The Bridgestone finished second in the open track portion of our test and a close third in the autocross. Like the Federal, this tire could easily make up the difference in transitional response with a close shave and some work with the tire pressures.

The Bridgestone Potenza RE-01R in our 17-inch test size is priced at $168 through The Tire Rack, and we feel it offers the best combination of street manners, track grip and autocross capability at a reasonable price. Welcome back, Bridgestone.


Falken Azenis RT-615:

The Benchmark Is Hard to Beat

The Falken Azenis RT-615 is a frustrating tire from an editorial standpoint. Not because it's tough to write about; it's just that we're getting bored with it winning every street tire autocross compare. Let's face it, "Falken Wins Again" is a pretty dull headline.

Of course, we're not seriously complaining. Why would we? From an enthusiast's standpoint, we love the Falkens. They're inexpensive - Edge Racing has our 17-inch size bargain-priced at $119 each - and they grip like glue. These tires make every car feel like a Lotus Elise.

The key to the Azenis is to realize that it?s not really that great of a street tire - and honestly, it really doesn't even like open track use very much. The Falken's tread design, with very little void area, can lead to interesting moments in the rain. On the flip side, it's extremely grippy, with excellent transient response in low or middling ambient temperatures. Out of the box on that first run of the day, these tires are simply stellar, but the grip goes away on subsequent (read: warmer) runs.

The Falken had the fastest open track average, most of this due to a smokin' fast first lap of 39.46 seconds. The lap times gradually increased from that first run, at a rate of about a tenth of a second per lap. By the last lap, this tire was behaving much more like the Yokohama or Bridgestone, requiring a bit more work to hit the apexes exactly.

The autocross testing also scored a win for the Falken, with its clean 42.79-second run the fastest time of the day. Giving the Falkens some time and cool water between runs helps keep the run times consistent: We found our fastest lap time on the last run of the sequence.


Competition Breeds a Better Tire

Tire companies keep raising the bar, so what was hot stuff four years ago barely cuts it in today's market. That's a good thing, because hardcore enthusiasts want a tire that does it all: Fast lap times, predictable handling and decent street manners. Oh, and it can't cost too much, either.

Where today's R-compound competition tires excel in on-track performance, the current crop of max-performance street tires - like the ones we tested here - are a more realistic option for many of us. It-s one of the few times you can have your cake and eat it, too.



Prepping for Action

To get our Saab 9-2X fit for tire test duty, we spent some time in the garage working on the suspension. The car had already received a pair of stout anti-roll bars, but it still exhibited a little too much roll and dive during hard maneuvers. With the stock struts and larger anti-roll bars, our lap times on the Ocala Gran Prix track averaged 40.58 - decent, but we knew that it could do better.

We started off the upgrades by replacing the factory struts with a set of adjustable KYB AGX units. In the past we have had great luck with these inexpensive shocks (a full set usually runs less than $300). The KYBs have proved to be tough, too, as the held up to an amazing amount of abuse on our Subaru Impreza rally car with nary a leak or failure.

However, there was a small snag with our application: KYB only listed struts for the 2002-'03 Subaru Impreza sedan. Fortunately a little bit of work allows these pieces to fit on the later Imprezas as well as the wagons, including our Saab-badged car.

The KYBs fit the front of 2004-and-up Impreza sedans as is, bolting on perfectly, but some work is needed to make them fit the front of an Impreza wagon. The wagons and sedans have slightly different lower mounting points, so if a sedan strut was simply bolted onto a wagon, you'd wind up with a little less than ideal negative camber.

This can be solved by using smaller aftermarket camber bolts. A quartet of OBX camber bolts gave us 3.0 degrees negative camber up front, which is more than adequate for track use. If only two bolts are used - one on each side - you get about 2.0 degrees negative camber, which is a great compromise setting.

In the rear, we also had to make some adjustments in order to fit the KYB struts to the later Impreza chassis. We had a few options, with the least expensive option requiring us to fit a pair of 20mm-diameter grade 8 washers between the top of the strut shaft and the strut mount itself. These washers recreate the slightly different profile found on the later strut shafts. A more expensive option is to find a set of 2002-'03 upper mounts and springs. Somewhere between these two options lies the Scooby921 Strut Spacers sold through Turn In Concepts for $23 complete. (Check out turninconcepts.com for details.)

The factory front upper strut bearing bearings are a little soft and can wear out quickly with a stiffer suspension, so while everything was apart we installed a pair of stiffer Impreza WRX STI upper strut mounts. We bought the pair for about $110 from Mastro Subaru.

Finally, we wanted to lower the car's center of gravity and firm up the handling. To accomplish this, we installed a set of Impreza wagon-specific springs sourced from Swift Springs. These Japanese-made springs lowered the car approximately 1 inch in the front and about 3/4-inch in the rear. This got rid of the "saggy butt" that Subaru and Saab wagons tend to get in stock form, but didn't lower the car too much. The Swift springs have rates of 185 lbs./in. at the front and 162 lbs./in. for the rear, which equates to about 25 percent stiffer than factory pieces. They can be purchased for less than $300 for the set of four.

Once our suspension was back together, we retested the car on track. Our new baseline on some well-abused Nitto Neo Gen tires was a respectable 40.08-second average. We dropped a full half-second with only a slight increase in vibration and roughness over bumps. As our technical editor's wife, Kim Schroeder, put it, "The Saab now handles like our MINI - cool!"


Street Tires for Competition

For a lot of people, changing tires before and after each autocross is a drag. There are few things that are less fun than installing and removing a set of tires under an unblinking sun.

In response to enthusiasts' wishes, many autocross sanctioning bodies have started implementing classes that require true street tires - the super-sticky R-compound, DOT-approved tries are specifically banned.

Most of these street tire classes, including those in the SCCA's Street Touring category, mandate tires with a treadwear rating of 140 and above. All of the tires tested here meet that specification.


By the Numbers

Code:
Brand Model Width (in.) Diameter (in.) Weight (lbs.)
Falken Azenis RT-615 8.7 24.0 25
Bridgestone RE-01R 8.6 24.2 25
Federal Tire 595RS 9.0 23.7 25
Yokohama Advan Neova 8.7 23.8 25
Results

Autocross Results
Code:
Yokohama Bridgestone Falken Federal Yokohama
Test order: 1 2 3 4 5
Run 1: 42.83 43.09 43.19 43.98 + 1 cone 42.93
Run 2: 43.36 43.37 43.14 43.69 43.62
Run 3: 43.19 43.29 43.22 43.67 43.13
Run 4: 43.83 + 1 cone 43.59 + 1 cone 43.03 43.59 43.69
Run 5: 43.01 43.15 42.79 44.18 43.24
Mean: 43.244 43.298 43.074 43.822 43.322
Fastest Run: 42.83 43.09 42.79 43.67 42.93
Rank: 2 3 1 4 control
Track Test Results
Code:
Yokohama Bridgestone Falken Federal Yokohama
Test order: 1 2 3 4 5
Lap 1: 40.43 39.88 39.46 39.74 39.65
Lap 2: 39.61 39.75 39.62 40.32 39.88
Lap 3: 39.95 39.83 39.73 40.25 39.73
Lap 4: 39.88 40.07 39.87 40.10 40.02
Lap 5: 40.04 39.95 39.88 40.40 39.79
Mean: 39.982 39.896 39.712 40.162 39.814
Fastest Lap: 39.61 39.75 39.46 39.74 39.65
Rank: 3 2 1 4 control

[CosmosMpower]

Weird, since when was the RT-615 better than the RE-01R and AD07? Also RE-01R's suck when they get hot, they need water almost every lap but GRM said they were very resistent to overheating?

[apex2apex]

Don't forget the Dunlop Z1 Star Spec, just got a set on the 8 and they feel real nice. Plus there's a $50 rebate going no right now, makes them a pretty good deal.

[Miatamoto]

Don't forget the Dunlop Z1 Star Spec, just got a set on the 8 and they feel real nice. Plus there's a $50 rebate going no right now, makes them a pretty good deal.

+1, I drove apex2apex's RX-8 on Sunday and the tires felt great. Tons of grip but not quite as good on turn in as the Neovas I'm running on my 8.

[CosmosMpower]

I agree, it felt like RT-615 levels of grip at a better price and apex2apex said they are much more civilized on the road (quiet and comfort) which is a big +. Plus 10-12 runs at La Grave didn't show ANY wear at all.

[apex2apex]

Tons of grip but not quite as good on turn in as the Neovas I'm running on my 8.

Could the relative slowness of turn in causes by full tread depth? The Z1 could probably benefit with shaving like all ST tires. Overall I am quite happy with them, esp with the saving over the Neovas and REO1R.