I believe you can fit a full size spare... (25" OD)
but the width of that spare tire cannot be much wider
then say the stock LE tire/wheel if retaining the cover
that lines the floor and covers the spare.
But I have not checked what maximum tire width
can be fitted under that floor/spare cover.
So someone else will need chime in
or you will need determine that maximum
spare tire width by yourself.
when you take off the full and have that spare try it? I also like to know and when I do take mine off I will try it. I know it will raise the plastic tray up by 4 inches. And I can modify to suit my needs.
Thanks HOUDAT for the suggestion. I too did not feel good about a donut in my 2016 corolla. I bought a wheel and a tire, plopped it in and it fit fine. I did flip the wheel over (front of the wheel facing the floor) once in so I could utilize the screw in mount from the donut to keep it from moving around too much (it takes a little modification to get it working like it did with the donut. The tools only fit snug on top when I cut the Styrofoam holder a little bit. I called around asking all over and everyone said this wouldnt work. It does, and if you drive a lot and far from home its nice to have. This shouldn't cost more than $250 bux total (for the wheel and tire) on the high end $85-150 on the low end (if you get a used/aftermarket wheel and / or used tire).