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Matching tire diameters important for C4S?

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YOUR RESEARCHMatching tire diameters important for C4S?

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POST 1 / ORIGINAL POSTEROriginal post

Searched the archives and couldn't find a definitive answer for this. Audi makes a big deal about matching tire diameters front and rear with Quattro, they claim that different diameters will screw up the center Torsen differential. Is the same true for Porsche's C4 and C4S? I want to go with a wider front tire to reduce understeer, but can't find a comibination that matches the diameter of my stock rear tires (295/30/18). The stock fronts (225/40/18) are within 3mm overall diameter compared to the rear. Is there some acceptable difference?

POST 2Original post

YES! It's why the C4 and C4S have the inflatable spare!

POST 3Original post

Quotes source post: 4600564

Yes, front and rears must be within 3% of each other's rolling diameter.

POST 4Original post

Quotes source post: 4600934

I believe the 3% diameter rule is not only required for the AWD system but also to ensure that traction control, PSM and ABS work properly.

POST 5 / ORIGINAL POSTEROriginal post

Thanks guys, that's exactly the info I was looking for!

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