I would not bother with your mates offer, a 190 tyre may look smart but it will slow your steering down and they are sometime slightly larger than the 190 section they claim to be ! trust me ! I had a rear puncture while 300 miles from home, my tyre was f##ked and the only place open on the Saturday afternoon had a " 190 Dunlop " which I had to have, so it was fitted, it looked H U G E ! and on the ride home to Cornwall the bike just didnt feel right, I got home ok and the next day I was riding safe and sensibly along my fav road and the next thing I know the revs hit the limiter and I was whacked in the left boot like being kicked by a Cart horse ! and the bike was all over shop, the long and the short of this was the "190 " was rubbing the chain all the way home ( not that it made any noise or I could feel it ) and on the back road the chain snapped !!!! Now I cant say this was 100% the tyre rubbing that caused it but there was a fair bit of tyre missing off the wall, and my chain was under the correct tension when I set off from Corwall ? and I use a Scottoiler. So I could just be unlucky but I would say Aprilia put a 180 as standard who are we to think we know better ?