For simplicity we label all wolves who originated from the American continent as "timber wolves".
With wolves that have been bred in captivity for generations, it is practically impossible to determine what kind of subspecies they truly belong to. In most cases they are probably a mix of many different subspecies - sometimes even including eurasian wolves.
Timber wolves come in all kinds of colours, many shades of brown and grey, but black being the most popular one. Their coat colours are also known to often fade over time to varying degrees, turning once deep black youngsters to various hues of white and grey with age. A pelt originally brown or grey might even pale to pure white.