Porsche will advise not to mix, makes, tread patterns or N ratings. This may affect your warranty dependent upon how vigilant your OPC is. They will not disclose what differences there are from N1 to N2 either, all you can tell is that N2 has improved performance in some area over N1. In an extreme situation there may just be enough difference for the car to react slightly differently - i doubt you'd ever get to this stage on the road, even in an emergency avoidance manoeuvre. Does it make a difference in the real world of UK driving - i doubt it very much. There is nothing in the UK MOT to stop you having a different tyre on each corner, provided they comply on speed ratings, load index, general condition and tread depth. I'd personally not have an issue mixing N ratings. There are plenty of older Porsches running non approved tyres. this is only my view - every time it gets discussed there are lots of views but no answers i'm afraid. I'd also ask Michelin whether they have any old N1 stock, or try a few other tyres places as they may have stock. Online suppliers.. [link=http://www.mytyres.co.uk]www.mytyres.co.uk[/link] [link=http://www.blackcircles.com]www.blackcircles.com[/link] [link=http://www.valuetyres.co.uk]www.valuetyres.co.uk[/link] [link=http://www.etyres.co.uk]www.etyres.co.uk[/link] no doubt lots of others. Micheldever / Bracknell tyres normally hold a lot of stock, so maybe they have some ? Just realised you have 19" wheels too, so i'll be in the same boat when my N1 rears need changing in the next year. I'll be mixing N ratings by the looks of it.