I have 2 inch Hanldebars. Will the mount fit?
Sorry, the included mount will not fit. However, you can use double-sided adhesive, or velcro to instal on a flat surface also
I have rubber valve stems. Is that a problem with this product?
These type of outer TPMS is not recommended for rubber stems. They will increase the pressure in the stems, so can cause the failure of the stems. You can use the inner tire type, such as Sykik SRTP400
Can you still use phone app also with this unit?
The sensors on units with display use radio vawes that are more accurate and more stable. So cannot be used through APPs that use Bluetooth connection.
My motorcycle requires 28psi front and rear. Does this fall within the range this TPMS will monitor without setting off the low pressure alarm?
Yes, you can reduce the low setting as low as you like
Can it be changed to psi or is it stuck in bar measurement?
Yes, you can change between PSI and BAR, also between Fahrenheit and Celcius.
how often you should charge it?
The display unit will need to be charged every 3-6 months. Depending on usage.