Can you replace 205 55 r16 tires with 215 60 r16 tires?
No, that is a horrible swap that would cause your speedometer to read 65.33 at a true 60 mph. Your power, fuel mileage, and handling would also be effected. A decent swap to a 60 series tire would be 195/60-16 and even then your speedometer would read 62.97. Stick with the OEM size.
NO, the last digits (R15 and R16) refer to the wheel (rim) size. If you change wheels you can install the 16" tires. A much better swap would be to install 205/65-16. The parameters except width will be almost identical to the 205/70-15 tire/wheel combination. Your speedometer will read 59.5 at a true 60 mph.
Yes, you can There will be about a 5% decrease in the tire diameter. 225 65 tires are 225mm wide and 146.25mm in height (65% of the width), while 215 60 tires are 129mm tall, which will affect the odometer and speedometer. When your speedometer reads 60 mph, you'll actually be traveling closer to 57 mph. Replacing the 225 65 tires with 215 70 tires would keep the diameter almost the same (150.5mm).
First off you will have to install different wheels. Assuming you have 16" wheels to install the tires on the answer is yes. This is an very acceptable substitute. Your speedometer will read 60.3 at a true 60 mph with the 16" tires and your engine will turn 4.2 more revolutions per mile which is negligible. Go for it as you have made a very good choice.
Although this is not a great swap it is acceptable. Know that your speedometer will read 58.3 at a true 60 mph. You will also have less pulling power. If you wish to go to a 70 series tire then a 205/70-16 is a much better swap. You speedometer will read 59.5 at a true 60 mph. Power will be effected very little.