Talk to me a bout the trail increase
There is also a 155/60R15 which is slightly smaller at 22.3" diameter if you really want to get maximum drop and lower gearing in your bike.
That tire would put the rear axle about 1.65" (42mm) lower than stock. But remember by dropping the rear axle that far without altering the front ride height it will also result in the head angle changing by around 1.6-degrees (reduced steering angle, and increased trail).
If I put the car tire and used the 155/60R15 and increased the trail would that also then make the steering better as if I put an easey steer? Just a thouhgt or am I off base