UmmBI wouldn’t run another step in those shoes. True, there’s no exact formula for determining when a pair of shoes has croaked, but keep in mind that most shoes won’t “look” worn out, even when the midsoles have lost half or more of their cushioning. That’s especially true if the midsoles are made of EVA (Ethylene Vinyl Acetate, a chemically formulated foam), a good cushioning material but one that tends to lose elasticity fairly quickly. Your 804s use several proprietary New Balance materials, which while no doubt excellent quality still don’t last forever.
It’s always better to be safe than sorry, even if that means buying shoes more often than one would like. It’s not unreasonable to figure that you should replace running shoes that get regular use once every six months or so. Particularly if you’re a moderately heavy runner, or if you run on hills a lot, which I bet you do in Portland. (Ever run up in the West Hills? I used to run there when I trained for marathons.)
It’s worth noting that the 804s are a trail-running shoe. Nothing wrong with that if that’s what you’re doing. But trail runners typically are a little stiffer than road runners, with a higher density (i.e., harder) midsole. So they don’t cushion quite as well. And all that impact聴probably 500 to 600 pounds per stride for a guy your size聴has to go somewhere. If the shoes don’t soak it up, it goes right up into your knees, not good for the cartilage. So if you don’t have stability problems, go with a shoe that has more cushioning. The Asics Gel Nimbus IV ($100) is a shoe with lots of heel cushioning. The New Balance 1022 ($100) is another high-cushion shoe. Incidentally, I think NB shoes are among the best out there.
New Balance 1022s available ; Asics Gel Nimbus’ .