275 on a 12" rim?! That must be stretched like a bish. I wouldn't doubt that the change in rear diameter has affected all of the VDC systems, causing the problems you mention.
You could try unplugging the battery to clear any codes, but I'm not sure that is going to "fix" the problems.
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Competition Clutch|Fast Intentions|Maxbore|NST|Setrab|Stillen|Tomei|Uprev| Z1
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