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campbellcj's Avatar
 
Join Date: Aug 1999
Location: Agoura, CA
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Question Switch from Hoosier R6 to radial slick

Hi all,

I have been running the Hoosier R6 (DOT R) and predecessors for quite a few years but would like to try real slicks, and I have the extra wheels to keep some of both around. Essentially identical sizes are available between the two Hoosier options. With my current POC classification - which is a bad joke anyway - I can "afford" the points hit. So those are non-issues.

Questions:

1) For a lightweight, fairly high-powered 914-6 would I be better off with the R80 (softer) or R100 (harder) compound, or perhaps a different compound at each end? I've read the R100 takes quite a bit of care and time to get up to temp and I imagine my light car would exacerbate that.

2) Will an alignment set up for the R6 (DOT-R) need to be redone for a radial slick?

3) Impact on driving style/technique?

4) Expected longevity difference?

Thanks in advance for any advice. I need some new shoes within 10 days, gotta pull the trigger ASAP.

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Chris C.
1973 914 "R" (914-6) | track toy
2009 911 Turbo 6-speed (997.1TT) | street weapon
2001 F150 Supercrew 4x4 | tow vehicle

Last edited by campbellcj; 06-14-2014 at 11:29 AM..
Old 06-14-2014, 11:27 AM
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1) I'd start with the R80. I use the R100 on the rear of the Cup car and it tears it up pretty good, but overheats the R80. I think a lightweight car you'd be fine.

2) I found that they were very similar in terms of needs. A lot less camber required than other slicks. I used about -3.0 front and -2.5 rear. Toe settings similar. Tire pressures will be substantially lower, in the range of 30-32psi hot which may have you wanting to change your spring rates.

3) They will take longer to come up to temp. Two laps for full potency. The challenge will be losing your "habits" to keep that extra cornering speed and not locking tires the first time with the lighter tire.

4) Well they won't last as long. On my lightweight they were cashed out in 12 heat cycles. In the cup car they get 8 max. On the upside they were good for 2+ second per lap.
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2001 GT3 Cup - "Pepin"
1999 Spec Miata
1996 993 RS Replica
2010 Harley 48
2013 Honda 250 CRF
1971 Norton 750 Commando
Alcon Brake Kits
Old 06-16-2014, 10:22 AM
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Thank you Chris, that is extremely helpful insight! I will try a set of the R80's and share my impressions.
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Chris C.
1973 914 "R" (914-6) | track toy
2009 911 Turbo 6-speed (997.1TT) | street weapon
2001 F150 Supercrew 4x4 | tow vehicle
Old 06-17-2014, 11:00 AM
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Sure thing Chris. Let me know what you think. FWIW I went from a 275/295 R6 setup to a 235/265 Hoosier Slick on my 2300# 911 and gained an average of 2 seconds per lap. This came from both grip and through getting the tire temps closer to optimal. (Could never get those wider R6's to full temp).

That said, this is what I'll run this weekend...

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2001 GT3 Cup - "Pepin"
1999 Spec Miata
1996 993 RS Replica
2010 Harley 48
2013 Honda 250 CRF
1971 Norton 750 Commando
Alcon Brake Kits
Old 06-19-2014, 07:42 AM
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Regarding temps, my 914 is even lighter than your previous 911 but I'm only running 225/245 R6's -- widest my modest flares will fit -- so the setup has worked well. I've got a set of R80's inbound and can't wait to try them! I plan to use-up my current R6's Saturday and switch to the slicks for Sunday (next weekend not tomorrow). Woohoo!
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Chris C.
1973 914 "R" (914-6) | track toy
2009 911 Turbo 6-speed (997.1TT) | street weapon
2001 F150 Supercrew 4x4 | tow vehicle
Old 06-20-2014, 01:23 PM
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Chris, be sure to give them a heat cycle and a 24 hour sit if you can. They will behave better at the limit in my experience.... They do take a lap or two to "come on" so warm them up well...
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2001 GT3 Cup - "Pepin"
1999 Spec Miata
1996 993 RS Replica
2010 Harley 48
2013 Honda 250 CRF
1971 Norton 750 Commando
Alcon Brake Kits
Old 06-23-2014, 08:30 AM
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Thanks again Chris. I just learned I'll only have 3 sessions per day vs. the usual 5/day and there's no warmup/practice (this is time attack/time trial). So now I'm torn between properly heat cycling the slicks Saturday morning or just running them all weekend.
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Chris C.
1973 914 "R" (914-6) | track toy
2009 911 Turbo 6-speed (997.1TT) | street weapon
2001 F150 Supercrew 4x4 | tow vehicle
Old 06-23-2014, 10:59 AM
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I haven't tried Hoosier slicks, but I run Goodyear radial slicks on my 914. I run lower pressures than those mentioned here, but maybe it's different for the GY's. My car weighs about 1900 and I'm running 23.5x10.5x16 up front and 25x12x16 out back, and run about 20 psi (measured cold in my case). FWIW.

Scott
Old 06-26-2014, 11:30 AM
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Scott - Thanks, I am damn glad you mentioned pressures as coming from the R6 I would have run the slicks too high. I found other threads including from Chris S. mentioning starting the Hoosiers around 19-21 cold aiming for 28-30 hot.
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Chris C.
1973 914 "R" (914-6) | track toy
2009 911 Turbo 6-speed (997.1TT) | street weapon
2001 F150 Supercrew 4x4 | tow vehicle
Old 06-26-2014, 06:51 PM
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I think I'm in love -- these will become my new standard tires unless the longevity is far worse than the R6. I ran them at 28psi hot today and they felt great. Didn't check temps but will do that tomorrow if I remember.

Thanks again for the inputs.
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Chris C.
1973 914 "R" (914-6) | track toy
2009 911 Turbo 6-speed (997.1TT) | street weapon
2001 F150 Supercrew 4x4 | tow vehicle
Old 06-28-2014, 05:52 PM
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I told you, they are like crack. Now if you run a DOT tire the limit will just feel greasy and unstable.

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Chris
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2001 GT3 Cup - "Pepin"
1999 Spec Miata
1996 993 RS Replica
2010 Harley 48
2013 Honda 250 CRF
1971 Norton 750 Commando
Alcon Brake Kits
Old 06-29-2014, 06:20 AM
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