There is a massive improvement that a smaller sized front tire will deliver. The Michelin Commander II 140/75 17 or the B'stone Exedra Max 130/70 17 will both make the bike feel hundreds of pounds lighter, dramatically improving turn-in, tracking and overall handling including much, much better cornering at any and all speeds. The 240 Exedra Max in the rear mated to its 130 sister (that sounds bad
) up front also reduces the rake angle from about 32 degrees stock to about 30 degrees, thus providing alot of the benefits already mentioned.
The 130 is that much better than the 140. I know, coz' I've run them both. The stock 150 size was selected by Triumph strictly for looks and it (they) actually compromises the R3's handling characteristics and overall behavior over the road. Either of the two front tires mentioned, should, properly mounted, balanced and maintained, give their users noticeably better mileage than any 150 sized tire, as well.