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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Wheels and Tires Forum Sponsored by The Tire Rack > Dunlop Direzza Sport Z1 Star Spec Vs. Bridgestone Potenza RE-01R



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      04-12-2008, 02:37 PM   #23
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Quote:
Originally Posted by AltecBX View Post
I don't plan to shave the tires.
Sounds to me like there is a set of RE-01R's in your future.

-Daniel
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      04-13-2008, 09:56 PM   #24
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We will see whether or not the Direzzas chunk when I take them to Buttonwillow on May 30th. Having met Daniel at CA Speedway I can say that he has strong opinions and appears to be extremely knowledgeable and a very talented driver. However please note that the difference between tires is probably only measurable by very accurate timing lights and by a driver who, unlike me, is capable of getting 100% out of his/her car.

Alec so far I am pretty happy with the Direzzas but have never driven on the RE-01R's. I suspect that either tire will be a significant improvement over the stock tires. Since I am not a pro and will primarily drive my car on the street, I personally selected the Direzza SS. They are less expensive and most likely will be very nearly as fast as the RE-01R.

Tire technology today is far superior to what we had even just a few years ago. What a great time to be an enthusiast!
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      04-13-2008, 10:24 PM   #25
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Originally Posted by 2e9x's View Post
We will see whether or not the Direzzas chunk when I take them to Buttonwillow on May 30th.
You're going for the Monty Memorial Weekend? Oh... I wish I could go. Right now, too many things in the air to be certain on that timing. YOU have a great time though, ok?

Quote:
Having met Daniel at CA Speedway I can say that he has strong opinions and appears to be extremely knowledgeable and a very talented driver.
Thank you for the kind words. I get pretty impassioned by product that does right by me. And this is me "toned down." Just imaging how I'd be if we were talking about.. oh... say.... Mac OS X?

Quote:
However please note that the difference between tires is probably only measurable by very accurate timing lights and by a driver who, unlike me, is capable of getting 100% out of his/her car.
This is really an important point. We're not talking great differences at this level of the market. The reality is, to the "un-indoctrinated" a stock 335 will prove to be an incredible car at the track without changing a single thing about it. So, fussing about tire models at this "novice" level is not that big of a concern.

As for my strong leanings towards Bridgestone? Brand loyalty from me has been earned by years of doing right by me. I've gone from the S-01, to the S-02 and the S-02PP. Later, to the S-03 (which I was not that crazy about) but later the 050A made up for it... and now with the RE-01R... I just think they are tremendous.

Quote:
Alec so far I am pretty happy with the Direzzas but have never driven on the RE-01R's. I suspect that either tire will be a significant improvement over the stock tires. Since I am not a pro and will primarily drive my car on the street, I personally selected the Direzza SS. They are less expensive and most likely will be very nearly as fast as the RE-01R.
Of course, now we'll have to meet up at a track event, run with transponders and see what happens..

Quote:
Tire technology today is far superior to what we had even just a few years ago. What a great time to be an enthusiast!
Indeed!

-Daniel
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      04-14-2008, 06:23 PM   #26
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Quote:
Originally Posted by FourPtDrift View Post
Oh really? Was this Dave Tirerack or his brother Robert Tirerack?

Excuse the goofiness... but your statement is just as absurd. WHO told you this? Does the person have a name? Did Tirerack release an official announcement saying this and that's why you're using the global "tirerack" as an attribution for the claim?

No. I'm sorry. Just because you may speak to one rep, doesn't cut it. Do some reading and research.

First off, Tirerack did conduct a run-off review between the Direzza Sport Z1 (granted, not the Star Spec, but I'll get to that in a moment) along with the RE-01 and two other products, the Yokohama Advan AD07 and the BF Goodrich g-FORCE T/A KD.

Here are the results in short order:



Now, you're probably jumping to remind me that this test does not reflect the Star Spec. Good. Let's examine some basic metrics of the Star Spec product and what makes it different from its predecessor.

First, let's see what Tirerack DOES say about the Star Spec (editorial if you like, from Tirerack)

"The Direzza Sport Z1 Star Spec is for drivers who donít want to wait as long for their tires to come in during initial runs, as well as drivers of lighter weight vehicles who are often confronted with the task of working tire temperatures up to the point of generating peak grip."

So, important note here. This is where reading between the lines becomes important. R spec and near R spec tires need to be brought up to a temperature before they come in their own. They don't work from a cold start. That's because serious track tires expect serious drivers to know how to manage their performance characteristics. So, the Star Spec is designed to "simplify" this process - especially for drivers of lighter vehicles. Hate to brake it to you kid, but this is NOT our car. The E9X is far from a light weight. That means the characteristics that caused the RE-01R to be dominant over the original Dirrezza are not addressed in the Star Spec. But, let's continue with Tirerack's editorial:

"The tire's internal structure includes two wide steel belts reinforced by JointLess Band (JLB) Technology spirally wound polyamide to provide strength, uniform ride quality and high-speed capability while steel cord reinforced, 2-ply polyester sidewalls help resist lateral deflection to provide responsive handling and cornering stability."

Now, how does this compare with the RE-01R?

"The tire's structure includes two wide steel belts reinforced by spirally wound nylon to provide strength and uniform ride quality and high-speed capability while the sidewalls are reinforced by steel cord that helps resist lateral deflection providing responsive handling and cornering stability."

Seems similar. Until you pay attention to the ingredients. Sorta like grocery shopping. I'll cut to the chase. The sidewall on the RE-01R is more than twice the deflection strength of the Direzza Star Spec. 200% greater. I know what I want on my +3,600 car. Not to mention there's the whole issue of tire sizes. Bridgestone has me covered. Dunlop? Not so much.

What's the RE-01R's ratings? Its a 140 Treadware AA Temp product. The Dunlop Direzza Star Spec? Oops. 200 Treadware. So... we have a stronger sidewall and STILL a stickier treadsurface with the Bridgestone product.

-Daniel
Hey Daniel,

Where do you get the data that the sidewall of the RE-01R is more than twice the deflection strength of the Direzza? Where do you get the 200% greater? Can you share your source data?

You do know that the treadwear rating is purely made-up by the manufacturer, right? There is no standard test...The manufacturer can put anything they want on the tire. In this case, is it possible that Dunlop put 200 because they need a treadwear of over 180 for the stock tire class of SCCA? And might that also explain why the Direzza works better cold...for auto-x?
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      04-14-2008, 07:05 PM   #27
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[quote=2e9x's;2488073]Hey Daniel,

Quote:
Where do you get the data that the sidewall of the RE-01R is more than twice the deflection strength of the Direzza? Where do you get the 200% greater? Can you share your source data?
Number of plies in construction available from manufactuer's website. Also reference Tirerack's descriptives whereas the the Dunlop is belted twice with steel and side wall wrapped with synethetic to a steel core while the Bridgestone runs steel from the sidewall through the belting (twice the layers).

Quote:
You do know that the treadwear rating is purely made-up by the manufacturer, right? There is no standard test...The manufacturer can put anything they want on the tire.
I think I mentioned this to you at Fontana. So yes, I know this.

BUT... the variance is not that great and it tends to be consistent through a manufactuer's history. Having done my time with SP8000's and later SP900's, I know how Dunlop rates is tirewear.

Quote:
In this case, is it possible that Dunlop put 200 because they need a treadwear of over 180 for the stock tire class of SCCA? And might that also explain why the Direzza works better cold...for auto-x?
I suspect the synthetics in the Dunlop are a constant through the tread depth whereas Bridgestone's varies through the tread depth (something Bridgestone has done, uniquely, since the S-02PP). This is why you see references to the Dunlop benefiting from shaving, but this is simply not done on the Bridgestone as it is engineered to vary density and treadwear with tread depth.

-Daniel
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      04-14-2008, 08:06 PM   #28
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[quote=FourPtDrift;2488307]
Quote:
Originally Posted by 2e9x's View Post
Hey Daniel,



Number of plies in construction available from manufactuer's website. Also reference Tirerack's descriptives whereas the the Dunlop is belted twice with steel and side wall wrapped with synethetic to a steel core while the Bridgestone runs steel from the sidewall through the belting (twice the layers).



I think I mentioned this to you at Fontana. So yes, I know this.

BUT... the variance is not that great and it tends to be consistent through a manufactuer's history. Having done my time with SP8000's and later SP900's, I know how Dunlop rates is tirewear.



I suspect the synthetics in the Dunlop are a constant through the tread depth whereas Bridgestone's varies through the tread depth (something Bridgestone has done, uniquely, since the S-02PP). This is why you see references to the Dunlop benefiting from shaving, but this is simply not done on the Bridgestone as it is engineered to vary density and treadwear with tread depth.

-Daniel
So you estimated the 200% number based on a description of the construction technique. Has anybody tested the actual sidewall deflection of both tires to determine how much stiffer one is than the other. The manufacturers do not report the tensile strength of the materials in the various tires so that makes it hard to draw any conclusions based strictly on how they describe their construction. You may very well be right and I would really like to find some empirical data to back up your hunch!

I would think that a tire with a 200% stiffer sidewall would have a WORSE ride and quicker steering response as opposed to what the Tirerack test noted. Further the people on SCCAForums.com who ran both found the Dunlop to be faster than the RE-01R and to have stiffer sidewalls. That seems counterintuitive to me.

I have read and re-read the description of the RE-01R and perhaps I am missing something. Can you show me where it describes the different layered compounds? They boasted about it with the S-02PP and S-03PP but I see no mention of it in the description of the RE-01R. If they do that on the RE-01R, that will definitely be my next tire purchase (or the replacement RE-11 due out soon) as I have put S-03PP's on a number of cars thanks to that technology.

Again I appreciate you sharing your knowledge and experience. I am really sorry if I am missing something here...
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      04-14-2008, 08:29 PM   #29
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[quote=2e9x's;2488627]
Quote:
Originally Posted by FourPtDrift View Post

So you estimated the 200% number based on a description of the construction technique.
I concede this is a small leap on my part... not very scientific, but like you rightly pointed out, we're dealing with extremely small tolerances here... but, yes, basically, if what is being communicated to me is a wrapping of twice the steel, then yes, I'm summarizing this as 200% greater substructure. Now, first hand, I can tell you that tire shops, and even my tuning shop, HATE mounting the RE-01R... and I suspect this has something to do with it. My last set of RE-01Rs came from a Bridgestone/Firestone dealer but I didn't have it mounted there. I picked them up to bring back to my tuning shop in West L.A., Lucent Motors. HOWEVER, the salesman at the Bridgestone shop did say to me that he was GLAD (I kid you not) that I was picking the tires up and that he wasn't going to have to mount them... and that he "felt sorry" for the person who would end up getting that job. Seriously.

AND, later, when the tired were mounted, Lucent staff basically said the same - its easier to install a 315/30 or even a larger 25 series on a 20" of ANY other tire make than a 275/30 19" sized RE-01R. And having witnessed the installation... I believe it.

Quote:
Has anybody tested the actual sidewall deflection of both tires to determine how much stiffer one is than the other. The manufacturers do not report the tensile strength of the materials in the various tires so that makes it hard to draw any conclusions based strictly on how they describe their construction.
While I am not a mechanical engineer, I have a suspicion that tensile strength (strength from being pulled) is not the measure in question here... but rather the resistance to warping or bending because of sandwhiching of layers. And no, I am not aware of anyone who has actually tested these elements.

Quote:
You may very well be right and I would really like to find some empirical data to back up your hunch!
I'm just going off the principle that steel that overlaps is stronger than steel that doesn't.

Quote:
I would think that a tire with a 200% stiffer sidewall would have a WORSE ride and quicker steering response as opposed to what the Tirerack test noted.
The RE-01R ride characteristics come from just not the sidewall engineering but the variable density in the tread... something that tirerack really doesn't comment on because it is proprietary to Bridgestone (called in Bridgestone marketing speak, "UNI-T"). This allows the Bridgestone tread to perform the same (minus water evacuation) irrespective of tread depth.

Quote:
Further the people on SCCAForums.com who ran both found the Dunlop to be faster than the RE-01R and to have stiffer sidewalls. That seems counterintuitive to me.
Wasn't this where I also read they were running the tires shaved? A shaved tire has less rolling resistance than a full tread depth tire. And a healthy set of RE-01Rs do have some noticeable rolling resistance to them. But use them on a heavy vehicle like the 335... and it works.

Quote:
I have read and re-read the description of the RE-01R and perhaps I am missing something. Can you show me where it describes the different layered compounds? They boasted about it with the S-02PP and S-03PP but I see no mention of it in the description of the RE-01R. If they do that on the RE-01R, that will definitely be my next tire purchase (or the replacement RE-11 due out soon) as I have put S-03PP's on a number of cars thanks to that technology.
From Bridgestone internally: They aimed to tone down the technobabble that seemed to be lost in the original marketing messages (hence the variance you see in message from how the S-02PP was sold in its day, vs, the RE-01R, today). You need to remember, when the S-02PP came out, it was a sportscar/performance tire... but because of some not so smart marketing decisions, the RE-01R was originally sold as a "Drifting Competition" product... and a bunch of technobabble on the tire ingredients wasn't caterig to the market. BUT... rest assured, Bridgestone does not abandon its patented technologies, and the RE-01R is full of unique tid-bits.

Quote:
Again I appreciate you sharing your knowledge and experience. I am really sorry if I am missing something here...
You didn't miss a beat. Not for a second. Yes, I was applying a little bit of conclusive thought on that 200% element, and you "caught" me on it... but I don't think my logic is that off base.

-Daniel
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      04-15-2008, 01:41 AM   #30
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So are the Dunlop faster than the Bridgestones?
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      04-15-2008, 02:31 AM   #31
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Quote:
Originally Posted by AltecBX View Post
So are the Dunlop faster than the Bridgestones?
Altec, we don't know. I believe they are not... but I don't KNOW they are not.

But the reality is, considering your starting with a stock AWD car... the tires are the least of your concerns for building a track car. Ultimately, should read all the information that has been posted here and online elsewhere... and go with what feels good for you. If you're looking for one silver bullet scientific argument for favoring one product over the other, in this example, I just don't think you're going to get it. Go with your gut. For me, its Bridgestone. For my friend who's been posting along with me in this thread, he's taking a chance on the Dunlop product. And in the end, we could both be right. I know this is probably not the easy answer you were looking for... but sometimes in life... there aren't always easy answers.

-Daniel
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      04-15-2008, 08:22 AM   #32
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Quote:
Originally Posted by AltecBX View Post
So are the Dunlop faster than the Bridgestones?
I too am sorry Altec...there is no obvious answer. If you read the Tirerack test results you will see that on their test course the Bridgestone was .3 sec behind the Dunlop. That margin is so slim that it is well within the margin of variability from one run to the next.

Here's my take on this...the RE-01R is a known great tire. On the other hand the Dunlop is the new kid on the block. Both tires are a quantum improvement over the stock RFT's. Neither tire is as fast as a true r-compound.

All indicators point to the RE-01R being the quieter, more civilized tire on the street. The Dunlop does have a very slight hum but it does not bother me.

Tread life on the Z1 is unknown. It is my sincerely held (although not factually supported) belief that Dunlop put a treadwear rating of 200 on the Z1 to help the tire be legal for SCCA auto-x street classes. You can tell that the Z1 SS was designed as an auto-x tire first and foremost. Personally I selected the Z1 over the RE-01R because I do more auto-x than track events. The Z1 was also cheaper than the RE-01R. Finally I worried about regretting my RE-01R purchase when the replacement RE-11 is released.

Rest comfortably in your purchase, regardless of which you choose, knowing that you are making a radical improvement in how your car drives. Best of luck and please let us know which way you decide to go.

Daniel - You are a true gentleman and I really appreciate your patience and graciousness as we worked through this discussion!!!! Hopefully you can make it to BW on 5-30-08.
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