I'm sorry, but no way is turning harder with a taller rear tire.
This decreases trail and quickens turning. In fact, you should not only go with the 240/55R16 ExcedraMax rear, a smaller front tire will further reduce trail and improve handling even more!
DO NOT lower the rear suspension! If your inseam is more than 30", consider 13" shocks over the 12" OEM.
LESS TRAIL = QUICKER STEERING.
MORE TRAIL = MORE IN LINE STABILITY AT SPEED.
Obviously the best trail setting has to do with what and how you ride. Trials bikes have the least because they never go fast and demand slow speed control and balance. Drag bikes have way more trail because they go high speed and in a straight line.
The R3R is a huge bike and it was designed with the rear axle .5" lower than the front axle (WTF?). Most likely it was done for litiguous reasons.
If you are an intermediate or better rider, do the tire changes. If not, you have no business riding a R3R or R3.
Burma