Tacx bushido not tight enough


I have a tacx bushido smart. I was using my outdoor tyre with no problems but I wanted to change it to a cheap tyre that I can trash. Someone gave me a vittoria zaffiro slick 700x23 for free so I thought Id try that, but when i come to calibrate it i cant get it tight enough to get the calibration dial to sit in between the white lines.

Any ideas why i cant get the roller tight enough on the wheel?

Could the tyre be too small?