I think it is a mess at Parts Unlimited rather than any DOT issue. Here is some more detail on what I saw.
The new printed catalog from from Parts Unlimited only listed the GTS23/24 -01 and -02 tires. These are bias ply tires for the AN400 and Silverwing. No tires in the size for the AN650 were listed there at all.
The online catalog screen I saw showed 3 lines:
GTS24-05 (the radial rear for the AN650). These were shown as available.
GTS23-25 (Yes, -25 rather than -05. No ordering status would come up. The counter guy called Parts Unlimited and was simply told that they were unavailable. No reason given.)
0340-0025 (the description of this item was "GTS23 120/70HR15" . The sizing is correct for the AN650 front radial tire).
I think someone at PU messed up by wrongly entering the Pirelli product code as -25, which is unavailable because it doesn't exist. In "fixing" the mistake, they entered the front tires under their own parts catalog number rather than the proper Pirelli number. Unfortunately their staff that answers the phone for dealer inquiries doesn't know enough to make the cross reference.
Fortunately I had a parts counter guy who was willing to hang in there and work with me, and Magyver's earlier post came to good use. I couldn't remember the number, but I did know the tire was mis-cataloged at PU. We found it, and PU sold a tire in spite of themselves.
As far as the dealers statement that a DOT issue was involved, I'm not making any accusation. But sometimes when a dealer's lips are moving you are hearing BS (um... that means Bad Stuff of course :roll: ). My personal guess is that the tire I get will be exactly the same as the GTS23-05 that I am currently riding on.