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Using slicks size 315 680 18 on a 997.2 GT3 with stock susp

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Old 05-30-2018 | 07:04 PM
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Default Using slicks size 315 680 18 on a 997.2 GT3 with stock susp

Just curious how this works out. I recently bought some new/used slicks and I'm worried there could be issues. Not worried about the front size but the rear is likely an inch taller than stock.

rubbing/I'm at stock ride height
camber bolts slipping because of the grip (stock)
gearing (or issues with dropping down to 2nd more than usual and or whipping car a bit more than one would like)
alignment: 2.5 camber front with 1/16 total toe out. 1.8 camber rear with 1/16 toe each side. Ride height at the center fenders is: 25 3/4 rear and 25 1/4 front. Sway is 1 off stiff front and in the middle out back.

Thanks for you help

Last edited by Fritz Flynn; 05-30-2018 at 07:05 PM. Reason: correction
Old 05-30-2018 | 10:05 PM
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Your rear's way too wide for a narrowbody. For reference: the RS runs 305-690-19 in Pirelli sizes.

There's space for a more tire on the inboard side, but you'll have to experiment with wheels and offsets. Difficult unless you run 3-piece wheels where you can change the barrel width easily...

It's a separate kettle of fish if your camber bolts are loosening--you can't even set up the car if the geo's moving all over the place. Question is why, and by how much? Losing .1 or .2 degrees after a track day is par for the course.
Old 05-31-2018 | 11:34 AM
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Originally Posted by CRex
Your rear's way too wide for a narrowbody. For reference: the RS runs 305-690-19 in Pirelli sizes.

There's space for a more tire on the inboard side, but you'll have to experiment with wheels and offsets. Difficult unless you run 3-piece wheels where you can change the barrel width easily...

It's a separate kettle of fish if your camber bolts are loosening--you can't even set up the car if the geo's moving all over the place. Question is why, and by how much? Losing .1 or .2 degrees after a track day is par for the course.
I'm currently running 315 cup 2s out back and they fit fine on some fikse wheels with likely a 67 offset. The offset on the wheels with the slicks mounted is a 65. I actually think the cup 2s may be wider than the 315 slicks (pirelli). I'm worried about the radius or the diameter which is at least an inch taller. I just don't want tons of rubbing. The previous owner of the setup mentioned his would rub a little but the car was lowered some.

I've also had the camber bolts slip a couple of times when I have sticky rubber on and obviously the slicks would be even harder on the susp. The bolts don't loosen they just slip.

Bottomline: just wondering how worried I should be running slicks on a stock 997.2 GT3 and have many people done it without issue?
Old 05-31-2018 | 12:25 PM
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I run 245/645/18 and 315/680/18, it's the only rear size I like for my 997.1 NB GT3. No issues with rubbing and my car is a bit lower, the extra rear sidewall makes the back end more compliant and easier to drive. With a 305/660 the car is all over the place and I have it setup pretty tight (rear sway bar almost full soft, front sway bar almost full stiff) I've gone through about 5 sets of these in Pirelli DH flavor already.
Old 05-31-2018 | 03:52 PM
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Originally Posted by CosmosMpower
I run 245/645/18 and 315/680/18, it's the only rear size I like for my 997.1 NB GT3. No issues with rubbing and my car is a bit lower, the extra rear sidewall makes the back end more compliant and easier to drive. With a 305/660 the car is all over the place and I have it setup pretty tight (rear sway bar almost full soft, front sway bar almost full stiff) I've gone through about 5 sets of these in Pirelli DH flavor already.
Stock shocks and springs?

THANKS!
Old 06-20-2018 | 12:23 PM
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Slicks worked out fine. It will be difficult using anything else going forward or definitely very good medicine. Things to note. When it's hot temps come up quick and starting pressures are pretty low (23 r 22f) Also when sliding they can overload the susp a little bit or bumping around does occur but with that said the car overall handles them fine which really says a lot about the stock susp.

Was hoping to get 12 sessions or so but after 5 sessions wear indicators are gone so these may not last any longer than hoos.

See vid from VIRs N course:

Old 06-20-2018 | 01:30 PM
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Originally Posted by Fritz Flynn
Stock shocks and springs?

THANKS!
Yes I believe my car is set a little lower than factory config too.
Old 06-20-2018 | 01:32 PM
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Originally Posted by Fritz Flynn
Slicks worked out fine. It will be difficult using anything else going forward or definitely very good medicine. Things to note. When it's hot temps come up quick and starting pressures are pretty low (23 r 22f) Also when sliding they can overload the susp a little bit or bumping around does occur but with that said the car overall handles them fine which really says a lot about the stock susp.

Was hoping to get 12 sessions or so but after 5 sessions wear indicators are gone so these may not last any longer than hoos.

See vid from VIRs N course:

https://www.youtube.com/watch?v=VBdw7dQhhdU
12 sessions should be doable if running stickers, 6-10 sessions for scrubs depending on how "scrubbed" they were when you got them. I usually get 2-3 days out of a scrub set.
Old 06-21-2018 | 11:33 AM
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Originally Posted by CosmosMpower
12 sessions should be doable if running stickers, 6-10 sessions for scrubs depending on how "scrubbed" they were when you got them. I usually get 2-3 days out of a scrub set.
Good to know.

I may have them flipped because the camber may be a little low (2.4 front 2 rear) but was surprised that the wear on the shoulder wasn't too bad.

Any good sources for scrubs out there today? Also where is the best place/price for sticker slicks?

Thanks!
Old 06-22-2018 | 04:56 PM
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you shuffle steer a lot
Old 06-23-2018 | 11:13 AM
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Originally Posted by ngng
you shuffle steer a lot
You are observant
Old 06-25-2018 | 11:27 PM
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Hi

ive been using the 305/680/18 rears on my 997.2 GT3 without any issues. The height and relationship to the front 245 is perfect for this car.

Good luck
Old 06-26-2018 | 10:59 AM
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Originally Posted by Rob996
Hi

ive been using the 305/680/18 rears on my 997.2 GT3 without any issues. The height and relationship to the front 245 is perfect for this car.

Good luck
Yep I've heard good things about the yoko tires and may try the 300/680/18 next. What compound and tire are you running?
Old 06-27-2018 | 08:55 PM
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I’m running Pirelli DH.. awesome trip..
Old 06-27-2018 | 11:21 PM
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A bit of a personal choice here... I've never found our GT3s short of rear grip. If a narrower rear opens up more suspension tuning options I would've opted for that.

The front is a different matter in the 997: if I could fit 275's upfront I would


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