preassure

Just thought I would ask the question on here. Just had 4 new tyres fitted 225/45W17. On the drive home I got the low pressure warning. In the dark I set the pressures to the top setting for unladen 42f/39r (I think) next day I drove it , it felt horrible and really noisy. Checked on line...

As above, can anybody help? There are loads of kracher ones on ebay for good money but there is so many different variants. 2.16, 2.61, 2.9. etc What preassure do i want to clean my car, including blasting the arches etc? i'd also like one with a detergent bowl for snowfoaming. let us...