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Help! 996 c4 tire options for the track

Old 12-28-2017, 11:10 AM
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Boostede36
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Default Help! 996 c4 tire options for the track

I really need the help of the tire guru's. I recently purchased a set of oz allegerita in 996 Gt3 spec (18 x8.5 and 18x11 as opposed to the 18x8.5 and 18x10 that were recommended) for my 99 911 c4. I purchased them with the intention of running a wider tire for the track. Now as I am ready to pull the trigger on tires I am receiving conflicting information that has caused me to second guess my wheel purchase. Due to the awd system, I was told that I can only run the recommended 225/40 and 265/35/18 tires. Anything else I will run the risk of causing damage to the differential and transmission. Does anyone know with certainty if this is true? If not what are some tire sizes I can run on my car to accommodate the wider wheels yet still stay within the correct tolerance that is recommended for my car. Your help is greatly appreciated. I called Porsche of North America and even my local dealership and they both informed me to stay with the stock tire sizes.
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Old 01-31-2018, 10:37 AM
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shekmark
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My C4S is a 997.2 and I have 11 rims with 305's and I believe the non-S has 295's. Are the 997 and 996 so different? What did you decide?
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Old 02-03-2018, 04:37 PM
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225/40 and 235/40 18 will work up front.

On an 11" rear, 265 is a bit narrow. 285/30 18, 295/30, and 305/30 18 are all better fits.

225/285 or 295 are closest matches in OD.

If using the 305 in back, it's best to match to the 235 up front.
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Old 02-04-2018, 05:26 PM
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Bill Verburg
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Originally Posted by Boostede36 View Post
I really need the help of the tire guru's. I recently purchased a set of oz allegerita in 996 Gt3 spec (18 x8.5 and 18x11 as opposed to the 18x8.5 and 18x10 that were recommended) for my 99 911 c4. I purchased them with the intention of running a wider tire for the track. Now as I am ready to pull the trigger on tires I am receiving conflicting information that has caused me to second guess my wheel purchase. Due to the awd system, I was told that I can only run the recommended 225/40 and 265/35/18 tires. Anything else I will run the risk of causing damage to the differential and transmission. Does anyone know with certainty if this is true? If not what are some tire sizes I can run on my car to accommodate the wider wheels yet still stay within the correct tolerance that is recommended for my car. Your help is greatly appreciated. I called Porsche of North America and even my local dealership and they both informed me to stay with the stock tire sizes.
The AWD restriction is due to tire height differential. Factory spec is fairly loose, I'd to actually look it up, but it's something like < 3 to 5% diff. The less the better though
225/40 & 265/35 are fine
235/40 & 275/35 are fine
245/35 & 285/30 are fine
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Old 04-28-2018, 12:02 AM
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What about 225/45 and 295/30 on the 8.5 front and 11 rear?
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Old 04-28-2018, 11:06 AM
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Originally Posted by Boostede36 View Post
What about 225/45 and 295/30 on the 8.5 front and 11 rear?
A 26" tall front tire in a track squat environment is likely going to give you issues. 225/40 and 235/40 are better ideas.
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Old 04-28-2018, 11:44 AM
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Thanks for the info. And I shoulnĺt have any issues with the viscous coupler overheating or affecting the awd system with the wider wheel? There are some strong opinions out there about changing the wheel sizes on these cars.
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