So after a few weeks ownership and a minor service completed I'm happy to keep the RR for a while. Love driving it despite the few electrical 'niggles'

My next move is to change the horrid 20" wheels. They're really not in good condition and to be honest I've never been a fan of the look.
I have the choice of a set of 7.5Jx18 fitted with 255/60R18 'All weather' tyres or a set of 8Jx19 fitted with 255/55R19 111V.

Is there any major difference between the 18s and the 19s in terms of driving?

I won't be doing any off roading so mainly for the road. The car is an Apr 2002 car and was originally fitted with 18s. Current:
2000 4.0V8 (LPG) P38 in Rioja red
2003 4.4 V8 (LPG) in Java black
2005 BMW Mini Cooper Park Lane in Royal grey
Gone:
2002 4.6V8 (LPG) P38 in Epsom Green
2002 4.4V8 Petrol (LPG) L322 in Giverny Green with Ivory interior

Not much difference between them. I've noticed after just putting my original 19's back on after years on 18's that it is a slightly firm ride on 19's probably due to the slightly lower profile although my pressures are on the firm side, if adjusted down might not be much difference.
Personally 19's look better than 18's but you probably get a better and cheaper tyre choice with 18's certainly for off roading 18's have an advantage but if that's not a concern it's entirely down to what you prefer.

Thanks, I think I'll go with the 19s. Current:
2000 4.0V8 (LPG) P38 in Rioja red
2003 4.4 V8 (LPG) in Java black
2005 BMW Mini Cooper Park Lane in Royal grey
Gone:
2002 4.6V8 (LPG) P38 in Epsom Green
2002 4.4V8 Petrol (LPG) L322 in Giverny Green with Ivory interior