correct tyre pressure??

[locx]

i'm driving kancil with 12" rims and recently changed to 13" sport rims. The question is, now what's the correct tyre pressure to apply to the tyre as i'm aware that correct tyre pressure is important for fuel consumption and for the life of the tyre itself..

the recommended from manufacturer:

front tyre : 145/70R12 = 32psi

rear tyre : 155/70R12 = 29psi

my tyre now :

goodyear gt3 165/60R13 on all side..

so what's the 'best' psi for this??is there anyway to calculate it or whatever??

 

[A329878]

i have seen the calculate before , if i'm not wrong is
Car weight in lbs / 100 = pressure in psi
this is for stock

If aftermarket wheel and tire add another 2-3psi
Example
3000/100 = 30 psi

 

[mini_cooper]

oh im using 175-50 13 inches rims ..how much air pressure should I pump ?