Our Wilkie name is a member of Clan MacDonald, whose tartan you can wear proudly!
The Brigadoon Industry peddles an awful lot of nonsense about clans etc. 'If your name is xxx you belong to Clan yyyy' is a very common example of this sort of nonsense, and is not to be relied on.
It's a very common misconception that all Scots belong to one clan or another, but it is simply not true. The clans were originally a social phenomenon of the Gaelic-speaking Highlands. Lowlanders born and bred did not belong to clans until Sir Walter Scott's popularisation of the 'romantic Highlands', followed by Queen Victoria's balmorality, kicked off a fashion for declaring yourselves to be a clan instead of being proud of being a Lowland or Border family.
I have two different lines of Wilkies, from different parts of Scotland. The name is a double diminutive of William, and is therefore a patronymic surname. All the early references to the surname are from the Lowlands - Midlothian, Fife, Lanark and Selkirk - and none from the Highlands. It may well be the case that some Wilkies were at a later date under the protection of or owed allegiance to Clan Donald, but this does not imply that all Wilkies were. In fact my mediaeval Lowland Wilkie ancestors would probably have been horrified at the suggestion that they had anything to do with any Highland clan.
I am proud to be a Lowland Scot with no Highland or clan ancestry for at least six generations, and I am not about to claim a spurious affiliation to Clan Donald or any other.
As for tartans, as I have said, there is no tartan police, and no-one is going to check whether or not you are 'entitled' to wear a particular one. If you want to wear a tartan, just pick one you like and get on with it. Most tartan designs are relatively modern anyway, invented in the 19th and 20th centuries.