I recently purchased a very original low mileage 996.2. Its a late 2001 with only 22k on the clock. I had negotiated on the price & budgeted to replace the tyres as the walls were cracked but thought I would check the date on them today. I believe they are very likely to be the original tyres from 2001 and still have a good 5-6mm tread left. To me this really confirms how carefully the previous owned had (or hadn't) driven the car. One has been replaced at some point as 3 tyres are 2001 and one is 2003. see pics below.