79pmooney

My approach - if I cannot see the hole from the inside when the nail/glass/whatever is removed, I do nothing. If I see evidence of the hole but no apparent cut cord threads, I simply put a tire patch over the hole to keep the tube from trying to bulge. More than that, I use a boot. On the road, usually a dollar bill (or as many as needed - I've used 5 for really big slashes; I always carry at least 5 of any demonination).

The dollar bill booted tires get sailcloth boots glued in with contractor's contact cement; the stuff you glue countertop laminates down with. (Real sailcloth from a sailmaker, not the "sailcloth" at Joann's Fabrics.) I save the cut tires and do a few at a sitting. When I have a tire off the wheel, I look to see if there is additional wear in the tread at any inner tube patches, If yes, there was cord damage and a real boot is needed.

Edit: sailcloth repairs done right are permanent repairs. I've ridden tires that got cuts 3/4" long at 500 miles until the tread was showing cord, thousands of miles later. Rode a mountainous Cycle Oregon on one such tire simply because as ride time neared, it was the tire I trusted most to grip on iffy downhill roads. Now, if I take that tire off a few times, the handling is hard on the sailcloth bond and I may have to break out the contact cement and refresh. But to save $70 tires? Not a biggie.