Well, there's winter air, and summer air...

Really, though, some of it comes down to personal preference.  I prefer
a bit high in the range because I don't mind a stiffer ride, and because
it reduces rolling resistance (improves gas mileage).  Anywhere in that
range will be fine; 40 sounds high, but I'll go as high as 36 in my
summer tires.  Winter, much lower...need that flex.

Dave Hinz

I got it from the back cover of the manual for my '01 Aero - 33 psi
for all loads and all speeds up to 160 km/h or 42 psi for over
160km/h. Presumably, once you get to 160 km/h, you have to send
someone out to pump up the tyres a bit before you can accelerate
further...

I also looked it up on WIS, but that is a bit confused, saying that
215/45/17 tyres are only fitted to the Viggen. It then gives 32/29
(front/rear)psi for all loads and speeds up to 190km/h. Above that,
you need either 38/35(front/rear) or 42/39 (front/rear)psi depending
on which market your car was sold in. Obviously US air is somehow
different to UK air.

I trust that's as clear as mud? It certainly is to me. I'm sticking
with my 33 all round!

Cheers,

Colin.