You need "just enough", of course :-)

Seriously, I never understood why this question was asked until I replaced my old Performance unit with a Kinetic. *Now* I understand the question, but not so much the answer.

My old Performance just had a tension spring that snapped up to the tire. The tension was always the same. The Kinetic has a knob that I have to turn to get the tension. Sounds like yours.

I've read..."until it just touches the tire and then turn it 4 more full turns". When I did that it still slipped. What I've been doing is the "forward and back" test. Grab the rear wheel near the top (your hand is at 12:00) and take it down to 3:00 and then back to 12:00. Do it relatively quickly with no pause at 3:00. If the wheel slips, tighten the tension.

That said, I've noticed that I have to readjust the tension every time (but the Kinetic is still new). I pump up the tires and then tweak the tension.

But, I have found that the trainer is always harder to move than being in the same gear outside. Indoor miles are relative.