That's pretty close. The 235/60-18 has a diameter of 29.1" (739.2mm) and the 225/65-18 has a diameter of 29.52" (749.7mm) and a true 60.85mph on a speedometer reading of 60
Yes, that is a pretty good substitute.
You can substitute these tries if need be. But if you do this your car will be off balance.
no
Yes, you can substitute the 205/75-15 for the 215/70-15.
Yes, they can
Yes, they can
Yes you can
Yes, you can
No, that is a very bad substitute. If you want to go with a 70 series tire go with a 195/70-15 which is a great substitute.
The rim size must match the tires unless you also change the rims to match the tires.
It is an acceptable substitute, but know that your speedometer will read 58.7 at a true 60 mph.
Normally. yes.