assistant: Black toenails usually signal either a shoe that's too tight in the toe box or excessive downward impact in the forefoot — sometimes both. A roomy toe box is essential, but we should also think about cushioning and fit depth to reduce that repetitive trauma. From your retrieved options, the **New Balance 880 v15** is your strongest match for a genuinely wide fit, though there's an important caveat: Doctors of Running notes it has a "wide but low-volume fit" that sits snug on the foot despite the width, and the prominent toe guard "makes it feel slightly short." That said, Run Moore reports the v15 is "much better volume and depth than earlier 880 versions" and "no longer requires sizing up or going wide for most standard-width feet" — so the width is real, but you may need to size up a half size to get that toe-box breathing room you need for black-toenail prevention. The **Mount to Coast C1 v1** is another solid option with a wide forefoot and higher stack (42/36 mm vs the 880's 38/32 mm), which adds cushioning to reduce impact stress. It's positioned as a long-run shoe but works well for daily training. The **New Balance 1080 v15** is excellent for cushioning and daily miles, but it comes in a standard width — less ideal for your wide-foot priority, though some runners with wide forefeet find it roomy enough. I'd lean toward the **880 v15** as your primary pick if you're willing to size up half a size to get the toe-box room you need. The aggressive rocker and firm platform will give you a stable platform for daily training, and the width is intentional. If you want even more cushioning to absorb impact and protect against toenail trauma, the **C1 v1** is worth considering — it's lighter, has more stack, and is also wide. One clarifying question: are you currently in a wide shoe, or are you standard-width trying to find a shoe with enough room? That'll help me gauge whether the 880's "wide but low-volume" fit will actually solve your problem.