my rear right tire is having very inconsistent pressure loss, one day it could drop 10 psi in a few minutes, the next it could remain at 42psi for a few days and then drop randomly. I had it inspected, only the outside of the tire, no nails, no bumps on the rim that could cause this either. A friend at cyclegear told me it could be my valve core. I went to a mechanic today and they screwed the valve core in more, but they said it was fine anyways. What in the world could it be? I dont want to go to a mechanic and pay them to replace my valve stem if thats not the issue

 

Yeah, could be valve-stem. Did you purchase the tire from CycleGear? If you did, they'll remount it w/a new valve-stem.

 

Take the wheel off and roll it around in a tub of water. You will see bubbles from where its leaking.

 

will this method show if the valve stem is the problem?

 

Yup. Any part under water will bubble. Give the stem a good wiggle.

 

The bathtub works great with about 10 inches of water.

 

thanks for telling me!