It is possible to find used 225 45 17 size tires on Ebay or Craigs List. Also check local recycle or junk yards to see if they might have used tires available.
Yes, you can use a 225-45-18 tires instead of 225-50-18 tires.
Yes you can do that.
Doubtful, the 225/65 tires are narrower and shorter.
Yes, they can. They must be mounted as a pair.
Yes, you can mount 225-60r16 tires on a rim made for 215-65r16 tires.
225-60-16 radial tires
Yes, they are just lower profile tires.
On a 2001 Toyota Highlander
Subaru Outback
225 70R15
Rotate tires 2 front 225 and 2 back 245
15 inch tires from 185 to 225 width.