Is she starting to Roan?
 

My yearling is Reg. as a Bay Tobiano, but lately as her winter coat is shed... shes getting more and more grey on her... :??????????????????????????????????????????

sorry, one of the pics didnt upload

What colour are her parents? She can only be a roan or gray if one of her parents was a roan or gray.

It depends. What colors are her sire and dam?

her sire was Shai's Commander... and he was a chestnut/rabicano, and her dam is El Painted Mist, she is a black/tobaino.

It's very likely that it is rabicano. Her tail is completely white, isn't it? That would make the distinguishing coontail impossible.

her tail is like 95% white..... theres one thick streak of black in it, and a small streak of a reddish brown...

Coon tails show up at the very top and don't extend very far down.
Like this:
http://www.pasofinohorsedirectory.co...achmentID=1376

But on her, you wouldn't be able to see it. I would say rabicano if her sire was rabicano. Post more pictures when she sheds out some more.

will deffinately do... im not sure if its just her winter coat coming out funny or what... as a filly she was a nice bright solid bay... but now the bay is covered in gray

Winter coats are funky too. My golden buckskin turned this ridiculous orange, almost sorrel colour this winter. Now, as she's shedding, she's got large patches with dark brown hairs mixed in so she looks sooty. Another member has a buckskin gelding that does the same thing when he sheds, then they both lighten up to normal later. Haha.