As the 17/18s would have quite a low aspect ratio, and I do not intend to track my car, it sounds like the PS4 will be a good choice for that set of wheels.

I have the OEM 16/17s on the car right now, and will one day need to replace the tyres on those (currently Potenzas) . . . but that's a slightly different question!

The Potenza/AD08R debate is reminiscent of the tyre choice for the Lotus Elise S2, which also has a front tyre size unique to that vehicle. The original OE tyre for the S2 was the Bridgestone RE040, with Lotus later moving over to the Yokohama AD07. These days people tend to run the unique size of AD07 on the front, with AD08Rs on the rear as they are available in the right size cheaper than the Lotus-specific AD07.

The general wisdom in the Lotus community seemed to be that the AD07/08/08R performs far better in the wet than you would expect for a tyre of that type, where the RE040 performs worse in the wet than you'd expect. I was never sure if the aggressive look of the Yokos led people's expectations to the conclusion that it would have zero wet grip and that for it to have any wet grip at all was seen as exceptional!

I'd be curious as to whether there's a consensus here as to which of the Potenzas or AD08R is better in adverse (read: British, rainy) conditions . . .