The only way tire pressure affects handling is if the pressure is low enough that the rim relative to the contact patch. I run pressures high enough to avoid pinch flats and tire flooping, because lower pressures 9toa degree) increase speed and definitely increase comfort.
Rim width and tire width matter, but unless the rim's internal width is the same as or close to the tire width it doesn't matter much. if the rim is too wide the tire will be stretched too wide, but most older rims are more like 15-20 mm, and most tires run 23 mm or more.