Ok thanks. I've been doing a quick bit of research in the meantime. I can see that I can get an 18" set of Pretoria reps from CMWheels for £440. If I then get 18" PS4s from Blackcircles, I can save £70 per tyre (fitted) on the PS4s compared to the 19" PS4Ss, plus an extra £40 off if I buy 4 (which obviously, I will!) That's a £320 saving, with a £440 pound outlay on wheels, so I'm looking at, effectively, £120 for 4 new wheels. Then I could sort the refurb of my Brescias at a later date.
In terms of what I'm looking to improve, it's mainly grip, especially in the wet, but mostly from a standstill in all conditions. I know you can't floor it in these FWD cars, but at the moment, it's ridiculous - I can only really start accelerating once I've reached a decent speed.
I gather longevity is supposed to be better on the Michelins than the Pirellis.
Besides the benifits of PS4s, I'm also interested in the fitment of these wheels. The Pretoria reps are 8*45ET, vs my Brescia at 7.5*51ET. willtheyfit.com says that the Prets will therefore be around 12mm wider, which sounds great with regards to filling the arches. However, the diagram looks like this:
I have read that the PS4s provide better rim protection than the Pirellis, but this diagram looks like it might be negated by the offset of the wheel. If this is the case, then I'd be more inclined to look at the 235*40 R18 PS4s, but these negate much of the cost savings I explained in my first paragraph!
What do you think?