Tires: rear tire inside wear, inflation pressure, tire rotation

Question
i have a 1986 toyota cresseda and the tires wear out on the inside.what would cause this?

Answer
Donald,

Unusual wear issues are caused by misalignment and aggravated by insufficient inflation pressure and insufficient tire rotation.

The wear you are describing is usually caused by excessive camber, but it could also be caused by toe out or "spirited driving".  If "spirited driving" partially describes things, then this points to a need to change ackerman - which is beyond most folks to be able to plan and execute, but it worthy of mention, because it will appear repeatedly even though the alignment is OK.