Originally Posted by geebee
Before you push the psi. higher get your lbs to tell you if the rims can handle it!!
There is a good chance that your rims are not rated much above your current psi. and it may result in a split rim or sudden failure whilst riding.
This is a very important point that is often overlooked by cyclists and even good bike techs. The rim must be the correct width and type for a given tire, and the rated PSI of the rim should not be exceeded. Most rim makers provide maximum PSI ratings for each of their rims, based on testing with tires of the correct size and type.
Assuming that your rim is rated for 100 PSI, there should be no problem running a tire rated at 90 PSI maximum at 100 PSI. Tire PSI ratings build in a substantial safety margin.
A tire provides its best performance at 15% deflection. For a 300 pound rider, on a given tire, 15% deflection might be obtained at 100 PSI. On that same tire, a 120 pound rider might obtain 15% (a slight visible decrease in the distance between the rim and the pavement when seated on the bike) at just 40 PSI. So, the "best" PSI for a given tire is different for each cyclist.