We have been over this in a few other threads.

A quick summary/update since my hypermiling started.

If its free (nitrogen) or near free, use it. If you have to pay anything more than a few bucks, don't bother. Since I've been getting 40/32 or 41/29 Hwy/city I think I'm a resonably credible soure on mileage.

2008 HHR SS No mods, 87 octane 8000 odo miles tire 34/35psi cold. I think 40psi cold is the max on the side walls. My ride is rough enough in the city. Wy go higher?

 

info on inside door says 30 psi cold...dealer sent me out with 35 psi....change to 30....35 felt like it was over working struts taking bumps hard...30 changed the feel of the car how it ride and holds corners...feels so much more sporty and safer......

 

I run 38 front and 35 rear on mine.
This is the stock 17" wheel with Uniroyal Tiger Paw GTZ 91W 44PSI max tires.
Fuel mileage is very good and wear should be also.
Mick

 

32 psi all four corners! I've played with as high as 38 front 36 rear and 35 all four and as low as 28 all four, but mine rides and handles best at 32

 

I run 205/60R/16's

Summer
32 Front
30 Rear

Winter .. Michelin Ice 3
30 Front
28 Rear

That tire size and pressures give me the best all around performance.

Be sure to always check Cold with a good gauge.

SF

 

Yep 30 is right when cold that's me all the way