SCCAForums.com

Good STU test coming up this weekend in Kansas City.  A few of us are going to be on the Dunlops.  We also have the tires to do a direct ciomparison test against the Yoks on an Evo...will report when this happens.  Probably not for a couple weeks yet when we get to Milwaukee. 

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Patrick Washburn
STU Evo
www.winghats.com

Rocky:

Because it appears that folks on the VW Vortex who have talked to agents at Tire Rack are starting to get scared of buying this tire in our stock sizes.

 

LOL...I would NEVER take advice or comments from VWVortex for..well, let's just say that, while there are some knowledgeable people on there, for the most part the "information" there is only partially informed and loaded with bias (and BS)

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VW R32
32 STX

vwawd:

John P:

I ran my first event (STU) on 245/40/17 StarSpecs today.  Wasn't too impressed actually.  They are at full tread, but they really felt particularly squirmy and vague.  Once you past the limit, you just slid.  Tough to recover. 

Although it was also rainy/occasional snow flurry ~ 40F today at Gateway in St. Louis; I'll need to give it a dry/normal temperature event to be fair.  I can say they felt like crap today, no grip anywhere.  Last place of five in STU against RE-01r's  and the Neova's, no other Direzza's.  I'm usually good for 2nd in my class and the occasional 1st.

 Had you put any miles on the tires before the event?  I ran a brand new full tread set a few weeks ago, and noticed that the tires grained significantly for their first 4-6 runs.  Once they cleaned up, the Z1 SS  times were consistent with RE01R's we ran in the first heat of the day.  

 

I had about 50 -70 miles on the tires before the event, but no hard driving until the event.  With the wet, there was no 'graining' to be had.  They did start to feel a little better on my last run, but I figured I was adjusting to the tire.  I'll have to hold judgement until another day, just wanted to throw out this opinion since I hadn't seen anyone report about a rain or really cold event on these.

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John P
'05 Suby STi

It seems that most of the recent feedback has been on unshaved Z1s.  Has anyone shaved their set (besides me--who wont get to run them until this weekend...)?

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Erik B.
Wisconsin Autocrossers, Inc
www.waiautox.org ___/\___/\___/\___/\___/\___
2007 Mazda6
2000 "Fozda" ZX2 S/R--STS Anti-Civic

Yeah...RichYung's were shaved when he won the ProSolo.  We decided to try full treads.

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Patrick Washburn
STU Evo
www.winghats.com

Lantern Rouge:

Rocky:

Because it appears that folks on the VW Vortex who have talked to agents at Tire Rack are starting to get scared of buying this tire in our stock sizes.

 

LOL...I would NEVER take advice or comments from VWVortex for..well, let's just say that, while there are some knowledgeable people on there, for the most part the "information" there is only partially informed and loaded with bias (and BS)

I know that, and have found far less usefull info on the Vortex than my old NASIOC Sube forums. But there are some actually really good folks there (TechEd for example - and a4tq - wink wink vwawd) that do know what is going on. And the XL vs SL load rating was a very valid concern that I admit I never thought of. I always thought that if it was in my OE stize, it would work. Naive of me.

nope -- sorry!

but here's a data point anyway, on unshaven 195/55-15s on 15x7 Kosei rims. STX cooper with -2.5 front and -1.0 rear camber and using of H&R coil overs.

mounted today (finally), so of course i went next door to the friendly skidpad, and spent 10 minutes getting the mold release off and assessing the tire's behavior. 

i had just removed last year's 225/45-15 RS2s which were amusing and terrifying yesterday at the season opener.  i was used to the RS2s, and they returned max grip last year of 1.09g at optimum temperature - shaven.  yesterday they returned a max of .98g on cold dry asphalt at a point where only the memory of tread remained.  they also earned me the unofficial "best drift show by a FWD car" according to the courseworkers...

the StarSpec tires endured the scuff exercise politely, without giving up any slides whatsoever (nor audibly complaining), and earned my confidence almost immediately despite being full tread and damned near an inch narrower!

without trying, at full tread depth, and just during the scuff in exercise, the Z1s returned 1.0g each way at 55 degrees ambient on fresh asphalt with a surface temp of about 60 degrees.  pretty encouraging for a first blush.

also, they do NOT tramline (the 225s would do a lane change automatically if left to their own devices on a worn highway truck lane), and they ARE quiet

so i reckon it's time to stop whining and go hunting WRX...

 

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Charlie Thompson
'04 JCW Cooper [STX]
NER Cannon Fodder

Patrick Washburn:

Yeah...RichYung's were shaved when he won the ProSolo.  We decided to try full treads.

 

OK...Thanks, Pat...thats good. Darryl called me yesterday and we talked about the Z1s, and his maybe getting some for his "Beh-Emm-Veh"...and how he'd heard that they somehow did not take well to shaving (specifically the *Specs).  I had not heard that...but it seems in retrospect that many here, now including yourself, are not shaving.

 

What is/was your rationalle for going full tread?  --anyone else who has decided on full tread Z1s can cretainly chime in as well...

 

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Erik B.
Wisconsin Autocrossers, Inc
www.waiautox.org ___/\___/\___/\___/\___/\___
2007 Mazda6
2000 "Fozda" ZX2 S/R--STS Anti-Civic

ebnrt:

What is/was your rationalle for going full tread?  --anyone else who has decided on full tread Z1s can cretainly chime in as well...

We started out last year on full tread Yoks, and they performed very well. Ended up running National's on that set (that had about 150 runs on them)...they tested out to be the best set we had against 2 new shaved sets!  Anyway, more or less just to get used to them.  We're going to test them up against a new set of shaved Yoks to see what happens.  Probably wait until Milwaukee for that...we're going to run the snow 'Lops on Kansas City this weekend. 

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Patrick Washburn
STU Evo
www.winghats.com

John P:

I ran my first event (STU) on 245/40/17 StarSpecs today.  Wasn't too impressed actually.  They are at full tread, but they really felt particularly squirmy and vague.  Once you past the limit, you just slid.  Tough to recover. 

Although it was also rainy/occasional snow flurry ~ 40F today at Gateway in St. Louis; I'll need to give it a dry/normal temperature event to be fair.  I can say they felt like crap today, no grip anywhere.  Last place of five in STU against RE-01r's  and the Neova's, no other Direzza's.  I'm usually good for 2nd in my class and the occasional 1st.

I ran the Chicago event this weekend in mostly similar conditions, except by the time I was on course it was dry, and I was very impressed with my star specs. They had excellent grip even at very cold temps. They never got really hot (single driver), but remained very consistent throughout. I thought they were very solid and easy to drive at the limit. I only drove them 30 miles before the event and they felt great from the start.

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Aytinc

TrEvoRS:

John P:

I ran my first event (STU) on 245/40/17 StarSpecs today.  Wasn't too impressed actually.  They are at full tread, but they really felt particularly squirmy and vague.  Once you past the limit, you just slid.  Tough to recover. 

Although it was also rainy/occasional snow flurry ~ 40F today at Gateway in St. Louis; I'll need to give it a dry/normal temperature event to be fair.  I can say they felt like crap today, no grip anywhere.  Last place of five in STU against RE-01r's  and the Neova's, no other Direzza's.  I'm usually good for 2nd in my class and the occasional 1st.

I ran the Chicago event this weekend in mostly similar conditions, except by the time I was on course it was dry, and I was very impressed with my star specs. They had excellent grip even at very cold temps. They never got really hot (single driver), but remained very consistent throughout. I thought they were very solid and easy to drive at the limit. I only drove them 30 miles before the event and they felt great from the start.

Shaved or unshaved?  Car type and modifications?  

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Ryan K

What pressure ranges is everyone finding the tires work the best?  Low 40s?  High 30s?  Low 30s?     I just picked up a street set for my 2 and it's going to be awhile before I get to do any real testing on them.

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Peter LeBlanc
'93 Mr2 ES

Shinomori I do not have enough test time to answer yet, but may I ask what size you are running?  That will help others answer I think.

I'm running 195/55-15s and I can say that in addition to returning encouraging lateral grip numbers unshaven out of the box they are very friendly street tires.  I am accustomed to some darty and loud summer rubber and don't mind the trade-offs but these Dunlops are better mannered over bumps, quieter, and less sensitive to road camber than any tires I have run.  Part of that may be the contact patch dimensions.

As part of my assisted self education on tires I've gone through varying specs and tried to understand what they really mean, particularly comparatively.  So I've gone through the mm width/aspect_ratio-diameter, and the quoted "Section Width" and the quoted "Tread Width" and tried to figure them all out.

I've found one more measurement helpful, and I have to gather the data myself.  I like "Contact Patch Width".

So I allow the car to roll backwards over a sheet of paper, and imprint a rolling image of the tread for examination and measurement.

Here's some data - some of it surprising to me - from the tires I have run.

Hoosier AS03 205/50-15             7 3/16          Quoted Tread Width is 8.0"

Hankook RS2 225/45-15              6 7/8           Quoted Tread width is 8.0"

Falken Azeni 205/50-15                6 5/8          Quoted Tread Width is 7.6"

Dunlop Direzza Z1 195/55-15          6 3/8         Quoted Tread Width is 7.6"

Sorry but I visualize in inches, I just haven't learned any real sense of millimeters despite having handled metric tools for a very long time.  All measurements were performed at 35 to 37 psi with a load of about 870 lbs (the LF corner of a Cooper S).  The wheel is a Kosei at 15x7.

Cheers,

Charlie

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Charlie Thompson
'04 JCW Cooper [STX]
NER Cannon Fodder

Good point.   I'm running mine on a '93 MR2.  195/55-15's.   The fronts are on a 6" wheel.  The rears are on a 7".

On most tires I've had good luck running the front 2 lbs lower than the rear.    Sometimes with a non staggered set it worked better to have the same pressure.

The tires in general feel great, but it feels like the pressures are not right.   

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Peter LeBlanc
'93 Mr2 ES

redwhale240:

TrEvoRS:

John P:

I ran my first event (STU) on 245/40/17 StarSpecs today.  Wasn't too impressed actually.  They are at full tread, but they really felt particularly squirmy and vague.  Once you past the limit, you just slid.  Tough to recover. 

Although it was also rainy/occasional snow flurry ~ 40F today at Gateway in St. Louis; I'll need to give it a dry/normal temperature event to be fair.  I can say they felt like crap today, no grip anywhere.  Last place of five in STU against RE-01r's  and the Neova's, no other Direzza's.  I'm usually good for 2nd in my class and the occasional 1st.

I ran the Chicago event this weekend in mostly similar conditions, except by the time I was on course it was dry, and I was very impressed with my star specs. They had excellent grip even at very cold temps. They never got really hot (single driver), but remained very consistent throughout. I thought they were very solid and easy to drive at the limit. I only drove them 30 miles before the event and they felt great from the start.

Shaved or unshaved?  Car type and modifications?  

 Unshaved on 17x9.5's. It is an 05 Evo RS with KW's (9k, 10k). I used them at 37 psi fr, 35 psi rear (have a rear adj swaybar), no rolling or chunking.

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Aytinc

ebnrt:

Patrick Washburn:

Yeah...RichYung's were shaved when he won the ProSolo.  We decided to try full treads.

 

OK...Thanks, Pat...thats good. Darryl called me yesterday and we talked about the Z1s, and his maybe getting some for his "Beh-Emm-Veh"...and how he'd heard that they somehow did not take well to shaving (specifically the *Specs).  I had not heard that...but it seems in retrospect that many here, now including yourself, are not shaving.

 

What is/was your rationalle for going full tread?  --anyone else who has decided on full tread Z1s can cretainly chime in as well...

 

 

More info here...

http://forums.bimmerforums.com/forum/showthread.php?t=969233

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Darryl Wrolson
1993 BMW 325is STX

I ran the 195/55/15 pinched on to a 15x5.5 Mini Cooper wheel this weekend.  Temperatures were in the 50s. Running about -1.8 camber.

I ran 5 runs back to back to get some heat in to the tires but according to my pyro they never go warmer than 80-85F.  The grip levels weren't as high as I had expected.  Has anyone monitored the temperature on unshaved Z1s?  What is the temperature sweet spot?   

lemons:

I ran the 195/55/15 pinched on to a 15x5.5 Mini Cooper wheel this weekend.  Temperatures were in the 50s. Running about -1.8 camber.

I ran 5 runs back to back to get some heat in to the tires but according to my pyro they never go warmer than 80-85F.  The grip levels weren't as high as I had expected.  Has anyone monitored the temperature on unshaved Z1s?  What is the temperature sweet spot?   

ya won't get that data from a New Englander this early in the season...  hell i don't bother with the pyrometer in april - what would be the point?

from prior years (and different tires) i'd be looking for the happy place in the 100-120 degree range, with greasiness appearing above that...

how much grip were you getting?  got any data?  i scuffed mine in at 1.0g lateral on cold pavement, so i'd hope you are getting at least that...

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Charlie Thompson
'04 JCW Cooper [STX]
NER Cannon Fodder

cmt52663:

how much grip were you getting?  got any data?  i scuffed mine in at 1.0g lateral on cold pavement, so i'd hope you are getting at least that...

Unfortunately, I have no data to prove my theory.  They just didn't feel as grippy as I expected, comapred to the Azenis I used to run.  Couldn't brake as hard or turn as hard as I wanted.  There was plenty of transitional grip but that is never the problem with the Mini.  Running back to back 35 second runs didn't seem to get they hot enough.

I was running 42psi front and 40 rear and the tread temps were pretty even across the surface.  There was a little rollover but the triagles on the sidewall and completely intact so it is pretty well controlled.  I thought about dropping the pressures to see if I could get more heat into them but was afraid of introducing rollover - freaking narrow wheels.

I guess I am hoping that the grip will increase significantly as temperatures warm up in the NE.  Otherwise I might have to get myself a set of 15x7s.

I just ran the 215/40-17 Z1's (pre-StarSpec) in STS yesterday for the first time on my 94 Integra GSR. I was VERY impressed with the grip of these tires. Even on my first run the rears heated up just fine (around 60' ambient temps, sunny, very windy). I ended up with about 35psi on all corners. Tires are mounted on 17x7.5 Rota Subzeros et45 (lightest of the non-ultra expensive 17x7.5 options at 16.4lbs)

in-car video (wind-noise, sorry) http://youtube.com/watch?v=hzVKarrfUng

 

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-Kelly
Rocky Mountain Region Solo / Time Trials - 94 Integra SM.
Apex RacingGroup.com