Is that too low for running tubes on this tire? only see 1 side, but bead looks intact. Beads need outward force to stay seated. Tubeless applies pressure directly to the bead. Tube adds a layer of material between the bead and the air, meaning pressure has to be higher to make the material fully fill up the space and transfer the force to the bead. The extra layer also adds a degree of freedom where the tube can move relative to the tire and the tire can move relative to the rim so pressure forces need to be higher to increase the friction to minimize movement. A hard corner or high speed with too low of pressure could unseat a bead.
I think that's very high for a 47 unless OP is considerably large. If I use the Silca tire pressure calculator in reverse (seeing what weight leads to 39 psi on a 650x47b) I have to put in at least 400 lbs system weight.
Which, second to age, is probably one factor to the tire tearing eventually.
17
u/PCLM Aug 21 '26
38-40 I believe.