Calculating Tyre Pressure:

Manufacturer Rating JDM SW20:
Front 83V 200kpa 29psi
Rear  91V 230kpa 33psi

Tyre load rating is designed weight at 35psi.
Manufacturer load rating is also the minimum required load rating, never go lower.

Front 83V = 487kg; 487/35*29 = 403.5kg
Rear  91V = 615kg; 615/35*33 = 579.9kg

New Tyre change example:
Front 87W = 545kg;
 404/545*35 = 487/545*29 = 180kpa 26psi

Rear  94W = 670kg;
 580/670*35 = 615/670*33 = 210kpa 31psi


Understanding Breakdown:
83V tyres can handle 487kg @ 35psi
Toyota says pump @ 29psi, means tyre only needs to support 404kg
87W tyres can handle 545kg @ 35psi
So the pressure needed to support 404kg is 26psi