Important - DO NOT put 315's in rears!!!!
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Joined: Mar 2008
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From: Russia
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I would if I would have 12 inch wide wheels...unfortunately my wheel are only made in this size...
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Joined: Apr 2006
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From: Austin
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I ran 245/30-20 (9 inch) and 325/25-20 (12 inch) on a 997 C4S with no problems. I realize the AWD systems are different between the C4 and the TT but I think the front to rear ratios were OK and didn't cause any differential problems.
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From: ATL, GA
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It can be ran is ran and will run with 325/25/20 on the Champion Wheels. They do it all the time and will tell you so. It is not ideal but it will work without a problem. Everyone who has the 20" setup runs a 325/25/20 setup from Champion and they sold a LOT of those wheels in the 20's for the 997TT's. Have you heard of one problem yet?
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Joined: Mar 2008
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The 315/25R19 rear matched up with the 245/30R19 front is well within normal running tolerance for the AWD 997tt. Remember, Porsche has to account for tire wear in their design and most tires have 10/32 of tread-that's 5/8' in diameter.
As many have said, maintaining the proper speed RELATIONSHIP between the front and rear is the issue. Even non AWD cars can have traction control issues if this relationship is not maintained. Good example of this is the C5/C6 Corvette.
Different tire companies recommend different maximum and minimum rim widths for best tire performance. For example, Yokohama recommends a narrower rim for their 315/25 than does Michelin. Even though the tires are the "same" size.
As many have said, maintaining the proper speed RELATIONSHIP between the front and rear is the issue. Even non AWD cars can have traction control issues if this relationship is not maintained. Good example of this is the C5/C6 Corvette.
Different tire companies recommend different maximum and minimum rim widths for best tire performance. For example, Yokohama recommends a narrower rim for their 315/25 than does Michelin. Even though the tires are the "same" size.
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After talking to porsche, audi techs over the year I would stay under 3% MAX
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The 315/25R19 rear matched up with the 245/30R19 front is well within normal running tolerance for the AWD 997tt. Remember, Porsche has to account for tire wear in their design and most tires have 10/32 of tread-that's 5/8' in diameter.
As many have said, maintaining the proper speed RELATIONSHIP between the front and rear is the issue. Even non AWD cars can have traction control issues if this relationship is not maintained. Good example of this is the C5/C6 Corvette.
Different tire companies recommend different maximum and minimum rim widths for best tire performance. For example, Yokohama recommends a narrower rim for their 315/25 than does Michelin. Even though the tires are the "same" size.
As many have said, maintaining the proper speed RELATIONSHIP between the front and rear is the issue. Even non AWD cars can have traction control issues if this relationship is not maintained. Good example of this is the C5/C6 Corvette.
Different tire companies recommend different maximum and minimum rim widths for best tire performance. For example, Yokohama recommends a narrower rim for their 315/25 than does Michelin. Even though the tires are the "same" size.
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Joined: Jul 2006
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From: Charlotte,NC
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Are you not doing all types off engine mods(big$$$)?? I mean were you not talking about a Werks air box in another thread? That thing is sweet but makes no HP and cost$$$$. Use some of that money and get the CORRECT SIZE WHEEL AND TIRE ALLREADY.........