You likely need to perform some string manipulation to get it to convert properly. If all of your strings are fixed width and follow the same pattern as provided in your example, the following is a possible way to get the conversion to work:
DECLARE @myString NVARCHAR(50) = N'Tue Aug 22 00:00:00 PDT 2017'
-- Month and Day + Year + HH:MM:SS using I assume 24 hour clock
SELECT CONVERT(DATETIME, SUBSTRING(@myString, 5, 7) + RIGHT(@myString, 4) + SUBSTRING(@myString, 11, 10))
If your data shows any pattern variances, please append some additional examples to your question.