tire math experts - I shud change my spare, right?

on the verge of putting my winter tires on, but here's the situation

last time I got new tires (April 2021) I changed tire size & bought 5, so my spare would match
... so if I put my winter tires on (which are the OEM size) can I leave that new spare mounted in the cargo area? would it be ok to use in the rear, if I get a flat? or shud I not risk it & put the OEM sized spare on?

both spare tires are new full size tires
the OEM spare was only used once for a cpl hundred miles
the winter tires have a few seasons on them

the OEM size is 225 60 18
tires on the car now are 235 55 18

so can I use winter tires that are 225 60 18 but keep my spare that is 235 55 18?

I guess I know the answer: "yes change all 5 tires" because, why not?