]I just spoke with the engineers at Bridgestone. Our beloved BT-45 in 100/90-18 is no longer available in V rated. They have discontinued it.
The two replacement options are BT-45 100/90-18 in an H rating or 110/90-18 in a V rating. The 110 is .75" taller and .5" wider. It is my belief that the H rated tire in the proper size would have less adverse effect on handling (mainly turn in). If you keep it under 130, it will handle the speed.
(UPDATE! The above replacement recommendations are INCORRECT. See post #7 below)
The rear 130/90-17 is still available in V rated.