Bit the bullet and got new set of PR4 GT's on the blue machine today. Discarded old PR4 front/PR4 GT rear with 16,000 miles. Maybe 20% 2-up riding on the old set. While I was at it, put new EBC pads on rear. I went ahead and removed the TPMS units and replaced the batteries on each. Fortunately, it was not as bad as I thought to replace the batteries, and is working well after the change-out.