I am working on a 3-tiered buttercream cake with fondant decorations.  I am concerned about the buttercream cracking/wrinkling in transit.  Any suggestions on how to protect my cake against this?  I did construct a cake pedestal with center post but was planning on stacking on site.  Thoughts on that?

There should be no problem—especially if you use the recipe “2 of everything “ found in the recipe section of this site   Cracking would be caused by the icing being too dry—not enough “fat” &/or the base board not strong enough vs wrinkles are from an icing too loose/to much liquid &/or again not strong enough board   By “ center pedestal “ I take it to be a center dowel onto which you will “thread” the tiers   There is no need for that when setting up at the venue  — it is used to help hold the cake together in transport   

I have no idea how many times I've posted this tutorial, but I swear by Sedar Yener's portable cooler.  It is practically free, keeps your cake nice and cold, and have taken much of the stress out of delivery.  The only thing I do differently is to leave one end open instead of the top so the cake can slide in and out of the box.  Much easier than trying to lower it down into the box then lifting it out again.

A tip I learned from kakeladi and -K8memphis, is to use tier sizes with more than two inches difference.  For instance, my go to sizes used to be 10", 8", and 6".  It looks pretty, but is not nearly as stable as 12", 8",  and 4", which also looks great.

Sandra I think some think it old fashioned but it definitely makes for a much safer delivery   My most requested/ordered  arrangements of tiers was 12,9,6   Or 16, 12,9,6  

I think 12x9x6 is the prettiest silhouette ever

OMG!  They selected 8, 12, 16!  I told my husband we would need a forklift to load it in the car!

Stack  2 tiers — either 2 & put them together on site  

Exactly as kakeladi said.  I would stack the two smaller ones because they would not be as heavy as the largest and next tier stacked together.