Tyre pressure need to find out my tyre pressure

Usually 34-38 Psi depending on solo rider or 2 up.
Handy link for all Avon tyres below
https://www.avontyres.com/en-us/tyre-care/technical/tyre-pressure-guidelines

One or more of the sensors on the valve stem is bad and needs replaced. (Most of the time).

I can calculate it with spreadsheet I made, call myself tyre-pressure specialist nowadays.
Depends on tyres maximum load and Pressure needed for that ( AT pressure 6pr 55psi/3.8 bar, 8pr 65psi/4.5bar or 69/70psi/4.75/4.8bar). and maximum speed of tyre given as letter mostly N to R for caravans.

Then from Caravan MPVW ( max permissable Vehicle Weight).
Or better real weight ( overloading is more rule then exeption and unequall load is possible.

But normal car tyres or XL/reinforced/Extraload are sometimes OK if they have enaugh maximum load for MPVW.
Will try to make picture of example.

Depends also on the kind of tyre.
For the maximum load of tyre nex kinds need next pressure , wich is called AT-pressure/maxloadpressure/reference-pressure , for up to maximum speed of tyre or if lower 160km/99m/h. This is not the maximum pressure of tyre.

Normal car tyre /standardload AT 2.5bar/36psi ( exeptions as low as 2.2)
XL/Reinforced/Extraload AT 2.9bar/42psi ( exeptions 2.8 and 3.0)
6PR( plyrating) /C-load AT 3.8bar/55psi EUR ( USA 50psi/3.4bar)
8PR/D-load AT 4.5/4.8 bar/ 65/69/70 psi
From E -load is not often used in Europe.

From this AT pressure you can calculate the needed pressure for lower loads . Made spreadsheet for it in wich I first add 10% to the assumed load before calculating.
Will give example picture

MENU-SETTINGS-TYRE PRESSURE-RESET TYRE PRESSURE.IF THAT DOES NOT WORK U WILL NEED TO VISIT DEALER TO RESET THE PRESSURE MONITORING SYSTEM......IT HAPPENS SOMETIMES.....

The required tyre pressure is established by the amount of load or weight that the tyre is carrying. Over or under inflation can cause excessive tire tread wear. The recommended pressures for your tyres are shown in raised lettering on the sidewall of the tyres.
Depending on what you are towing, you will know how much additional weight is being placed on the cars rear tyres, and you can adjust the pressure accordingly.
Personally, When I am towing, I increase the tire pressures by about 5 psi just to reduce sidewall flexing and create a more stable towing package.
Hope this helps.

2002 VW Polo 1.4

Tyre: 165/70 R14
- Front tyre pressure: 2,2 ... 2,4 bar
- Rear tyre pressure: 2,0 ... 2,6 bar
- Spare tyre pressure: 4,2 bar

NEVER the same pressure on both tyres !!
Usually, rear tyre is larger and/or carries more weight (you), therefore needs a much higher PSI. On a Hornet 250, 600 or 900cc it should be 36psi FRONT and 42psi REAR. - check the manuals.

Yup nice question. For any vehicle accurate tyre pressure will give you better tyre life, low running cost, etc. Here is a chart for car tyres click here.
For bikes i havent found any chart. basically in india rear tyres having 100/90 18inch maximum tyre pressure is 32psi. front tyre having 2.75P or 80/90 18 inch uses 24 psi pressure. and do check your tyre pressure twice a month.