What does standard transport lead time refer to?

Standard transport lead time refers to the amount of time it takes to deliver your finished part from your plant or warehouse to the requested customer location.

What does process lead time refer to?

Process lead time refers to the amount of time it takes to produce the part in your production facility.

What does supplier Tier 2 lead time refer to?

Supplier tier 2 lead time refers to the amount of time it takes to get raw material or components from your Tier 2 supplier in order for you to manufacture your demanded part. 

If there are multiple Tier 2 providers for a part which lead time should I enter?

Enter the longest Tier 2 lead time for the part.

When do I use production family lead time defaults?

If many of the parts of your production family share the same Supplier Tier 2 lead time and Process Lead time, set the lead time defaults during the creation of the production family. Then when you link a part to that family, the product data sheet (PDS) for that part will be automatically populated with those values.

What if some of my parts in the production family have different lead times?

Simply override the lead time defaults values that get populated, by entering lead times on the individual product data sheet for those parts.

What if I change the default lead time values of my production family at a later time, will those values be rippled through all the parts in the family?

No, since overriding values may have been stored for some of the members of the production family at an early time, we wouldn't want to lose all that information.

Why isn't there the ability to set a transportation lead time default for a production family? 

Transportation lead times will always have to be defined on a individual basis because one part may go to two different plants.  Thus each would have a unique transportation lead time.