I've done full circumference belt showing several times. However, unless I am planning a long tour I go to the wear bars.

I do 30 to 40+ K a year and go through about two sets between the various bikes. The last set was on a XL1200T. they were at 11K. The Buell was only at 8K. The Ultra was at 22K. I have a tire changer and do my own. That substantially reduces tire cost by getting them at discount on line with free shipping and no sales tax.

I have a touring set on hand for a Road Glide but traded just before needing to change them.

Side note: As tires age they get harder and will do more miles. However the traction is lower. Just be aware and less aggressive in rain. The Lance Armstrong team aged the tires in a cold damp basement in France for several years before using. They were more interested in durability than traction.

 

If the cord ain't showin', I'm still goin"...
I like to live on the edge...

 

If ya ever get the chance to cut a tire apart after the cord is showing. You will be surprised how thin the rubber is from the exposed cord to the air inside the tire.

 

This is the lowest so far. The new 140 is so much better than that worn out 130. Glad went up one size. Just a whisper away from the belt. Changed my rpm about 100 at same speed.