Can you replace 215 65r 17 summer tires with 225 60r 16 winters (on their own rims)?

No, you cannot replace 215/65R17 summer tires with 225/60R16 winter tires, even if they are mounted on their own rims. The two tire sizes have different diameters and aspect ratiOS, which can affect the vehicle's handling, speedometer accuracy, and overall safety. It's important to use tires that are compatible with your vehicle's specifications as outlined in the owner's manual.