Technically: Yes, IF you change all 4 tires andyou have the recommended rim width for the new size, and the new tire has a high enough load rating (especially for pickups). It may be hard to find a tire this much smaller with the same load rating.
They are narrower and a lower profile tire, so handling and ride might be different (in fact, it's likely that both will be worse).
Your speedometer will be off by 5%. It will read too high. Also, your odometer will go too fast by (the same) 5%, so any mileage-based warranties will expire sooner.
For all these reasons, many (most?) tire shops will not do this size substitution.
You can substitute these tries if need be. But if you do this your car will be off balance.
Yes, they can as long as both are the same on each axle.
Yes, that is a pretty good substitute.
Normally. yes.
Yes, you can
Normally, yes. The 65 tire is slightly shorter that the 70. A much better swap would be to go with a 225/65-15.
no there is too much height difference
It is an acceptable substitute, but know that your speedometer will read 58.7 at a true 60 mph.
Yes, that is reasonable as long as both sides match.
Yes, if you mount as a pair. Both tires on axle must be the same
Possibly, check they don't rub anywhere while steering.
215/70/r15, 215/75/r15, 225/70/r15. I think that some may have also came with 14inch wheels. I have put tires as large as 225/75/r15 or as small as 205/75/r15 on an 84 without any issues.