Should I do a measurement without the threaded portion? Thinking back now, most of the spindles I've seen use bolts.

Getting off topic here but... I also just noticed a big chunk missing from my rear Gatorskin, so time to try out those Compass 32's. I'm estimating that I did somewhere between 1,000-1,400 miles (1,600-2,200km) in about three and a half months. Is that reasonable tire life?