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> What Wheels/Tire set up on your GT body race car?
jmz
post Aug 18 2017, 11:21 AM
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What's everyone running for wheels and tire size on their race cars?

Do you go with a staggered setup or square?

What size wheel?

What size tire?

What do you run for rains?

So far I've tried

15x8&9 with 245x40x15 DOT comp tires on all four corners Maxxis Victra RC-1

16x10 with slicks on all four corners. Dunlop 265x60x16 slicks


I'm most likely going to run 16x8&9 next weekend with 245x45x16 on all four corners with RA-1s.

I've got some 15x9&11 that I may try down the road with my local club

and when I run COTA with SVRA later this year I'll have to go to 15x8 on all 4.

I'm new to this car and am still learning it and learning to race.

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stownsen914
post Aug 18 2017, 07:26 PM
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I'm running 16x11 front and 16x12.5 rear with slicks 23.5x10.5-16 front and 25.5x12.5-16 rear. Have been running Goodyear, switching to Hoosier now that Goodyears aren't available anymore. I'm doing track days and club racing, so no rules limitations. I've found the car to be very balanced with this setup.

Scott
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Cracker
post Aug 19 2017, 02:55 PM
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For what its worth and realizing this might not apply to you depending on what limitations you have by class rules - I run 17's (R7)- its a better performance tire size and the selection is excellent. The worst size for available tires is probably 16's - started with them and quickly switched. I hope to be able to eventually run square with 275/35-17 - time will tell...

F: 24/40-17 (7)
R: 275/35-17 (9)

Tony

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MikeSpraggi
post Aug 20 2017, 01:00 PM
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I'm running 15x7 205/60/15 front and 15x8 225/50/15 rear with RA-1s and loving it. I also have a set of 16x7 205/55/16 and 16x8 225/50/16 using 888s. Can't get the 205/55/16 in 888s now. Don't like this combo too much.

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jmz
post Aug 21 2017, 09:44 AM
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QUOTE(MikeSpraggi @ Aug 20 2017, 02:00 PM) *

I'm running 15x7 205/60/15 front and 15x8 225/50/15 rear with RA-1s and loving it. I also have a set of 16x7 205/55/16 and 16x8 225/50/16 using 888s. Can't get the 205/55/16 in 888s now. Don't like this combo too much.

Attached Image



What are you running for a front spoiler/splitter up front? My car came with a rear spoiler similar to yours but was missing it's front. I pulled it off since I'm running just the normal 6-gt front bumper setup and was concerned about balance.

Thanks for the datapoint.

I'm running in the rain it looks like this weekend so trying the Ra-1 toyos and mounted on 16x8&9 fuchs. 245x45x16 all the way around.
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jmz
post Aug 21 2017, 09:45 AM
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QUOTE(Cracker @ Aug 19 2017, 03:55 PM) *

For what its worth and realizing this might not apply to you depending on what limitations you have by class rules - I run 17's (R7)- its a better performance tire size and the selection is excellent. The worst size for available tires is probably 16's - started with them and quickly switched. I hope to be able to eventually run square with 275/35-17 - time will tell...

F: 24/40-17 (7)
R: 275/35-17 (9)

Tony

Attached Image



That car looks like its all business!
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slivel
post Aug 21 2017, 03:37 PM
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Fuchs 16x8 front with Hoosier 245/45/16 and 16x9 rear with 274/45/16.Attached Image
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tygaboy
post Aug 21 2017, 04:11 PM
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QUOTE(slivel @ Aug 21 2017, 02:37 PM) *

Fuchs 16x8 front with Hoosier 245/45/16 and 16x9 rear with 274/45/16.Attached Image


Wow... That's beautiful!
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MikeSpraggi
post Aug 22 2017, 12:04 AM
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QUOTE(jmz @ Aug 21 2017, 08:44 AM) *

QUOTE(MikeSpraggi @ Aug 20 2017, 02:00 PM) *

I'm running 15x7 205/60/15 front and 15x8 225/50/15 rear with RA-1s and loving it. I also have a set of 16x7 205/55/16 and 16x8 225/50/16 using 888s. Can't get the 205/55/16 in 888s now. Don't like this combo too much.

Attached Image



What are you running for a front spoiler/splitter up front? My car came with a rear spoiler similar to yours but was missing it's front. I pulled it off since I'm running just the normal 6-gt front bumper setup and was concerned about balance.

Thanks for the datapoint.

I'm running in the rain it looks like this weekend so trying the Ra-1 toyos and mounted on 16x8&9 fuchs. 245x45x16 all the way around.


Here are some before and after front spoiler photos. Same piece of fiberglass, just repaired..the beauty of glass.... This setup is very stable for me at high speeds.

Attached Image
Attached Image
Attached Image

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Cracker
post Aug 22 2017, 07:03 AM
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Regarding the spoilers, splitters, spoiler and wings....

My on-track experience leads me to believe:
1) The duckbill spoiler is of no tangible performance value but it does greatly help the aesthetics of the rear on a 914. That air is dead as dead as can be...
2) The spoiler is a decent place to mount brake cooling ducts but not much else..it increases drag vs a stock valance. The increased stability is probably a function of the car being slowed down due to the increased vertical surface area. I run this air-dam too...
3) A wing needs to be way the hell up there to grab clean air - the bottom of my wing is 1" (and should be higher) above the highest point of the roof line.
4) An actual splitter must be able to support at least 250 pounds of direct vertical force to remain stable at speed. My first effort fractured at 160 mph (mid-corner T9 RA) and I thought I had lost a wheel!!! IF you install one - bring it back all the way to the front suspension cross-member - there is more to aero than just the leading edge reveal.

Not meant to offend and step on toes - just sharing what I have learned...

T
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jmz
post Aug 22 2017, 08:51 PM
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For posterity here are a few shots of my car in different configurations.

15x8&9 fuch/minilite

16x10 on all four corners in current silver and past green with front/rear spoiler.Attached Image
Attached Image[attachmentid=617
350]Attached Image
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Cracker
post Aug 22 2017, 09:20 PM
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striking teener...

T
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jmz
post Aug 23 2017, 10:26 PM
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QUOTE(Cracker @ Aug 22 2017, 08:03 AM) *

Regarding the spoilers, splitters, spoiler and wings....

My on-track experience leads me to believe:
1) The duckbill spoiler is of no tangible performance value but it does greatly help the aesthetics of the rear on a 914. That air is dead as dead as can be...

...

T


...so in your opinion, do you think that a little ducktail spoiler could be run without a front spoiler? ...sure cannot do that on a 911. I'm talking about one like on the yellow car or the one you can barely see on my the green version of my car in the photo above.
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Cracker
post Aug 24 2017, 05:29 AM
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Spoiler or splitter? If you are referring to a splitter as a spoiler - no you can not but if you just mean a spoiler as an airdam - yes. PM me with your contact info if you want to discuss this - far easier and more precise.

Tony

QUOTE(jmz @ Aug 24 2017, 12:26 AM) *

QUOTE(Cracker @ Aug 22 2017, 08:03 AM) *

Regarding the spoilers, splitters, spoiler and wings....

My on-track experience leads me to believe:
1) The duckbill spoiler is of no tangible performance value but it does greatly help the aesthetics of the rear on a 914. That air is dead as dead as can be...

...

T


...so in your opinion, do you think that a little ducktail spoiler could be run without a front spoiler? ...sure cannot do that on a 911. I'm talking about one like on the yellow car or the one you can barely see on my the green version of my car in the photo above.

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jmz
post Aug 24 2017, 06:12 AM
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QUOTE(Cracker @ Aug 24 2017, 06:29 AM) *

Spoiler or splitter? If you are referring to a splitter as a spoiler - no you can not but if you just mean a spoiler as an airdam - yes. PM me with your contact info if you want to discuss this - far easier and more precise.

Tony

QUOTE(jmz @ Aug 24 2017, 12:26 AM) *

QUOTE(Cracker @ Aug 22 2017, 08:03 AM) *

Regarding the spoilers, splitters, spoiler and wings....

My on-track experience leads me to believe:
1) The duckbill spoiler is of no tangible performance value but it does greatly help the aesthetics of the rear on a 914. That air is dead as dead as can be...

...

T


...so in your opinion, do you think that a little ducktail spoiler could be run without a front spoiler? ...sure cannot do that on a 911. I'm talking about one like on the yellow car or the one you can barely see on my the green version of my car in the photo above.




Tony, I will P.M. you. to attempt to be clear, I was curious about running a ducktail spoiler meaning the little rear spoiler like on the yellow car or the green version of my car with a standard GT front air dam like on the silver version of my car. I chose to remove my rear tail since I didn't have any aero up front.
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Cracker
post Aug 24 2017, 06:28 AM
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LOL. Yes. You can run that with no front-aero all day. I hadn't had my cup of coffee this morning yet! (IMG:style_emoticons/default/biggrin.gif)

T

QUOTE(jmz @ Aug 24 2017, 08:12 AM) *

QUOTE(Cracker @ Aug 24 2017, 06:29 AM) *

Spoiler or splitter? If you are referring to a splitter as a spoiler - no you can not but if you just mean a spoiler as an airdam - yes. PM me with your contact info if you want to discuss this - far easier and more precise.

Tony

QUOTE(jmz @ Aug 24 2017, 12:26 AM) *

QUOTE(Cracker @ Aug 22 2017, 08:03 AM) *

Regarding the spoilers, splitters, spoiler and wings....

My on-track experience leads me to believe:
1) The duckbill spoiler is of no tangible performance value but it does greatly help the aesthetics of the rear on a 914. That air is dead as dead as can be...

...

T


...so in your opinion, do you think that a little ducktail spoiler could be run without a front spoiler? ...sure cannot do that on a 911. I'm talking about one like on the yellow car or the one you can barely see on my the green version of my car in the photo above.




Tony, I will P.M. you. to attempt to be clear, I was curious about running a ducktail spoiler meaning the little rear spoiler like on the yellow car or the green version of my car with a standard GT front air dam like on the silver version of my car. I chose to remove my rear tail since I didn't have any aero up front.

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jmitro
post Aug 24 2017, 04:44 PM
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thread kinda morphed from tires to aero, but I think it's worth noting that in sanctioned racing, one would be rules-limited to tire size and aero (among other things).

For instance, when I raced BMWCCA in Mod class, the wing height was limited to no higher than horizontal with the roofline.

Otherwise, I think Cracker's observations are correct when restrictions don't apply
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jmz
post Sep 7 2017, 04:32 PM
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QUOTE(jmitro @ Aug 24 2017, 05:44 PM) *

thread kinda morphed from tires to aero, but I think it's worth noting that in sanctioned racing, one would be rules-limited to tire size and aero (among other things).

For instance, when I raced BMWCCA in Mod class, the wing height was limited to no higher than horizontal with the roofline.

Otherwise, I think Cracker's observations are correct when restrictions don't apply



Yes for sure rules will dictate. I'm looking at SVRA tire rules and really not sure what I will run when I run with that club. Here is what they say:

Group 8 - Molded Treaded Tires
Minimum aspect ratio of 45, except
certain car Make and Models, which
have specific tire requirements listed
in their Supplemental Regulations,
tread depth—no less than 2/32”
remaining, at all times, over 75% of
the tire.
Wheels may be of an alternate
material but must be of period
design. They must be the correct
diameter and width as specified
within the Supplemental Regulations
of the Make and Model.
Tires may not extend beyond the
fender opening at the highest point
of the tire.
Approved tires:

There are no specific sizes listed because of the large diversity of Group 8 cars.
All Group 8 cars must use similar sized tires to what was used in the day, which is pre 1973.
Using oversized tires is unacceptable and when in question, SVRA’s determination shall be
the final word.

Avon: ACB9, ACB10, CR6Z
Goodyear Eagle: 5.50/15 G12 or G12A
Hoosier: Street TD & Speedster
Any Treaded, DOT approved Tires with a UTQG of 100 or greater with appropriate
Speed Rating and a minimum Aspect Ratio of 45
Note: Group 8 must use approved full molded treaded tires, regardless of what
specification tires a car may have competed with in a prior race series.
For Toyo RA1’s and Nitto NT01’s, please see page 6 of this document
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HalfMoon
post Sep 9 2017, 04:21 PM
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QUOTE(slivel @ Aug 21 2017, 05:37 PM) *

Fuchs 16x8 front with Hoosier 245/45/16 and 16x9 rear with 274/45/16.Attached Image


Curious how your splitter performs. I'm designing one for my car and I also have a Sheridan standard widebody. I hap planned on using five supports but it appears as if your not using any. Riveted to the lower lip and attached to the pan about midway to through the wheels?
Has the Sheridan glass cracked any on ya?
TY
D
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jmz
post Sep 11 2017, 09:07 PM
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I don't mind bouncing between aero and wheel/tire so hope nobody else does.

Spoke with SVRA today and R888R are not on endangered list yet so should be able to run those in 2018. I'm going to try 225x50x15 on front and 235x50x15 on rear when I run SVRA and probably my local club too.
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