Will replacing a tire with one size smaller, hurt anything?

FWD Ford Fusion, hit a giant pothole, has a 225 size tire, but the local used shop only has 220(?) he said its one size smaller and he ll throw it on for me until they get a 225 in stock. We can t afford a new $120+ tire right now, otherwise we obviously wouldn t be asking this question. This guy sells nice used ones for $20-$40 a piece installed and balances the wheel as well. I ve bought numerous tires from him so I trust his work and word, but would like a second opinion since I ve never ran an odd size tire.

The car is FWD, and the tire is the passenger rear.

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