Tyre pressures 235 45 17"s

[vw754]

What would you guys say...235 45 17"s fitted on sport 5 star genuine audi wheels... ive gone on door pillar sticker 38 psi allround,dealer says 36-38.
Decided to check as my car was only doing 100 miles on 16 quid local @ 91.9 pence per litre (approx 26 m.p.g !!!!) found my tyres had 30 psi allround,at 38 psi it feels a bit of a bumpier ride

OH! nearly forgot A4 TDI (B6) 130 BHP.

(originaly had 15 inch alloys!)

 

[arthurfuxake]

38 is for a fully loaded car ie 5 people and luggage. 32 is for normal day to day driving with 1 or 2 people. I used 35 as a compromise, because some days I'd be loaded, and others I'd be empty, but my tyres have worn in the centre which suggests that they are over-inflated. Gonna drop down to 32 for my new set of tyres as I spend less time heavily loaded now.

 

[fjtwelve]

Running at 34 on Continentals just now, used 36 on Goodyears before.

 

[huggis]

confusing area; my new A6 was delivered with the pressures approx 10psi over what the sticker stated. still struggling to find out what they should ideally be! The ride quality is very poor so I'm keen to find out.

 

[vw754]

if i lower the car, do i keep the same tyre pressures?

 

[denzelburner]

Most tyre manufacturers have a set psi for their own tyres, the one noted on the door pillar would be for the ones that come originally fitted to the vehicle when new, so if the tyre on your 17"'s are audi standard, then you should be able to stick with the same as on the pillar.
Pressure is supposed to be read when the tyre is at ambient temperature, so not really after a lenghty run, better before a trip. If you're fully laden then the pressure is increased by between 4-7psi depending on the tyre manufacturer and load.
You shouldn't need to change the pressure when lowering the vehicle, as it will still have the same tyre wear as when it wasn't lowered.
Hope this helps