Factory rear wheel is 17", and DR650SE's do not come w/ a factory tach, only speedo/odo.
Congrats on the purchase - quite a deal you scored even if it does need some TLC!
I live in Monroe and work in Redmond. If you'd like to check out another DR as part of figuring out your bike, feel free to send me a PM and we can figure out a way to meet up.
'09 DR650SE, well equipped for adventure travels
'10 FZ1, commuter and sport touring weapon
'99 XR250R, fledgling trail bike