as a simple rule to follow, tyres that are bigger, higher in profile need less pressure compared to tyres that are narrow and lower in profile.

As for passenger car, i normally try to vary the pressure between 29 - 35!

35psi is hard.....and 27 is soft!

Different story for motobike..which has lower air volume in their tyres, they probably have different scale range to follow....maybe between 40-50psi

My mountain bike( a bicycle) need around 50 to 60psi ...and my tour de langkawi race bike is somewhere between 100 to 120psi!

So, i hope you got the idea...the lower the volume, the higher the pressure! There is no right numbers....