Hi, I am considering the switch to 19-17 setup on my 990. I consider buying a pair of new wheels. This will permit me to have off-road-mixed wheels (21-18) and tarmac-only wheels (19-17) for a quick switch. I found Alpina second-hand at 700£, maybe negotiable. What do you think of the idea? Or shall I just buy an additional pair of 21-18 if I want to have this comfort? Or just change tyres when I need to? Is it easy to switch, or it requires a big setup change (suspensions, etc....)? Thanks.