with Softfever fork of Bambu studio you can do settings more precisely:
Modification post :
I have tooth idlers, I ll measure them and if it’s ok I try to replace the smooth idlers. I come back in 4 hours after the end of my print and my manipulation to report my experience with you 
My tooth idlers measure:
inner-diameter :5.4
outer-diam:11.9
border : 17.85
I’d know if it is good only after disassemble the Bambu’s smooth idlers. Actually I’m printing, but after it’ll be mechanic time ^^
Modification post number 2 :
I’m trying to understand how to disassemble the idlers without broke something 
If you have ideas : I take 