Mtb Psi

webbhost said:

quick question - servicing my friends bike tomorrow, but i'm not sure what PSI his tyres should be?

What PSI is ideal for a mountain bike? I know my racing bike is 110 PSI but if i remember right, the 2 are different.

Thanks for whoever replies first!

Recommended PSI will be on sidewall. If riding mainly on pavement run them at the higher end. Running at the low end off road can cause pinch flats.

It depends on a few things...probably one third of the pressure in a roadie.
I'm only 60kgs and run 26psi in the front and 30psi in the back. If your friend is heavier then more pressure. As a general rule you will run at the minimun pressure, that is keep going down until you start to get pinch flats and then put it a bit above that threshold. The reason being that the tires are part of your suspension system and too much pressure gives a harsh ride. Of course if the riding is all on good road you will use more pressure for less rolling resistance.
Halcyon1

his tyres said 40 min 60 max PSI so i inflated to 50PSI.

should be OK at that, mid point of the guide pressure is fair enough

My Larsen TT (non-UST) limits are 35psi-65psi. I way 90kgs and I pump the fron to 45psi and the rear to 50psi. I tried running them at 40psi but got alot of pinches.