Not cleaned but a small update.
I had some racing ralph in 29x2.25 laying around so in a lazy sunday morning I mounted them.
On a 18mm internal rim they go out at ~53mm with tubes. Max of my clearance !
Such a cushion ride on the trails ! But feel a bit slow on tarmac.
I will get rid of the racks to lighten the build, will see how long this setup last. I also need to remount the tires tubeless.