In the absence of Glasgow Warriors' Stuart Hogg, who is away with the Lions, Tonks lines up at full-back, having made 21 appearances in the RaboDirect PRO12 this season, since his switch from Northampton Saints.
And Tonks is convinced that his international selection justifies his move to the Scottish capital.
"It has been a good move for me," said Tonks, who scored a try in his last match of the season against Newport Gwent Dragons.
"This was the aim, the reason I came to Scotland, to play regularly. If anything happened off the back of that then brilliant. Fortunately it has.
"It's great to play in South Africa. It's such a rugby-mad country. The environment is fantastic. This is a good opportunity, but it will be tough."
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