While I was pretty sure there wouldn't be a problem, today I found out for sure that we can run 13" tires on the Mirage and clear the brakes and such. I swapped on a set of winter tires I had from a Civic, 13x5.5" rims with @38mm offset, 4x100mm bolt pattern, with Winterhandler 175/70R13 tires and they fit just like the originals. I had planned on swapping the tires over to a nicer set of aftermarket rims I have but they were already mounted and balanced so I gave it a shot. Specs on the tires are almost exactly the same diameter as stock, but much, much better in the snow.
Ride is not half bad either, pretty much the same except the better traction seems to keep the suspension from moving around quite as much, maybe. I've been planning all along to run 13's on the car after the stock tires wear out and I'm still going to go with that.
So far so good, though I'm scratching my head as to why after 3 individual trips, all with engine stops and starts, the TPMS light hasn't come on steady yet. Pretty much same as always, on for a second or so when the car starts then it blips off. I don't remember these wheels having sensors, and I certainly didn't program anything, so it seems like there's every reason for the light to be on. I'm not complaining, just curious.