My feet are a tough fit and would serve better at a brick and mortar, but it's hard to find time with my twin girls, so I chanced it on a size 13 Trask Gary Chukka. Nice looking shoe but way too much room in the heel even with double socks (and made the feet hot) and I was blistering up badly. My feet are slightly under 11.5 inches and 4.25 inches wide, which makes them, technically speaking, a size twelve and a half. But 90% of the time, I fit in a 13.
Maybe chukkas and boots are different. In any case, I risked another online buy and ordered a pair of tan Lacoste Sherbrooke Hi 13 chukkas in 13. If they don't fit, I may try a 12 or get my butt down to Nordstrom.