Tunnel MTU

[rosenblumb]

What should we be setting the MTU on our tunnel's to so that they are the same on both sides?  I'm using only Cisco hardware on my tunnels (I have a few sites each has one for that site).  My "show ipv6 int tunnel 2001" shows that the MTU is currently at 1472 (my internet is coming in via DSL straight to an ATM interface in the router).  On other routers that are coming in via the FE ports it shows as 1480.  I would like to set the tunnels statically so that its all universal across my sites and also so that I'm not getting any fragmentation through the HE network.  Thanks!