I have not purchased a 5th for spare yet, but yesterday I removed the OEM spare and took some measurements. It appears a full diameter donut will fit in place, allowing the stock storage compartments to remain. I also believe a full 225/65R17 if I remove the upper foam storage caddy. I have not decided which route Im going, but Im definitely going to replace the OEM spare with a proper diamater tire.What about your spare? Did you buy 5 tires? If you had a flat, then the spare will not have the same circumference/diameter as the other 3 tires. This may wreck havoc on your traction control and stability control which monitor how fast your tire spins relative to the other tires. You change circumference, you change how fast a tire spins.
If the bigger size fits in the spare tire location, then i may go for this down the road. I always like increasing ground clearance in IFS/IRS vehicle via tire sizing. How much has it affected your speedo?
Re: Speedo - Surprisingly I found the 65-75mph range to be spot on using a GPS for comparison. Perhaps the factory config was at the outer limit, and the .9" increase in diameter corrected this?