Most common alternative size for both -
175/65r14 (23") & 185/55r15 (23") are the identical 23" diameter tires, & they open up options for both sizes. The Mirage should be sent to America with these two tire sizes. They are way more common. I see no need to purchase different rims when looking for other options.
Just using Walmart as an example today (have one in my home town area), & I don't have a Discount Tire or another large tire vendor nearby -
Walmart offers 333 tire options for 175/65r14.
Walmart offers 247 tire options for 185/55r15.
I am not sure how many tire options are seen as good?
I have had zero problems finding factory size 165/65r14 tires when I need them. The options are not as many, but that makes shopping for tires just easier in my mind.
Some vendors may carry more 185/55r15 tires over the 175/65r14. If I were buying 175/65r14 tires, I wouldn't be looking past Walmart in my case. Prices are good, mounting of new tires purchased is free, and lifetime balance is $14/tire. If I lived near a Discount Tire, I may be shopping there.
I do shop beyond Walmart for 165/65r14 tires, but I have bought them there, too.