I would prefer to not raise the suspension at all, I’m partial to lowering my HHR, so 1 1/2 inches would be good. These spacer rings are for lifting at the coil spring and spring perch in the front strut, which will marginally alter the centre of gravity, so to firm up the sway a TurboTechRacing rear sway bar should also be installed.
I would raise the front first, then see what is required to level the HHR, we forget the the stink bug stance is approximately 1 1/2 inches.
and so possibly only the front end needs to be raised.

 

Raising a HHR more than 1 inch with spacers in the suspension is asking for trouble. The geometry offset on the suspension is going to put stress on things such as CV axles and wheel bearings.
I suggest you look at the size tires you are currently using. The HHR can handle a tire up to 26.3 inches in diameter. If your current tire size is less than that, then using "taller" tires would in effect raise the car without affecting the suspension geometry.
If you need to raise it more than 1 inch, then you should look for another vehicle with better clearance.

 

X2

I would go to Tire Rack and Check specs of your current stock tires as well as other possible's.
You say you have a 2009 LT with a 2.4L
That could be 2 possibilities,
.
A ..1LT with the 2.4L option ...ie. 215/55/16

Or
A .. 2LT with a different stock tire size 215/50/17

You then Know the 17" tire will fit with clearance and if you now have 16" stock tires you could gain the difference safely.
Also you need to look at the tread widths because if you go with another different size the "Tread" width could be a problem
Keep in mind the Aspect ratio .... of 55 and 50 on the stock sizes.
I don't know if the 18" SS tire application would be a problem on an LT or not but you could check it out also.
My thought would be to stick with the narrowest tire you can find in the 26.3 Over All diameter limit.
Be sure to compare with what you have now to tally the correct gain.

Silverfox

 

SS 18” tires are the same diameter as the 17” 2LT tires


18 inch SS Cobalt rims

17” 2LT rims

 

a taller tire is a good idea.
I tried this on my Nissan. I did it as needed, bought and supplied tires that were available and roughly matched the factory parameters. An increase in tire radius of just 1.3 centimeters (0.51 inches) has a distinct visual impact. Distinct and very beautiful. When I installed the new standard springs, the beauty was added, the small Nissan rose by about 1 cm additionally due to the absence of spring subsidence. It seems that the girl (or grandma, which in my case is closer to the truth) put on high heels and began to look slimmer. As a result of these changes, discomfort did not appear, all systems work normally.

 

Hi, Thanks for a lot of answers. I should mentioned that the car is driven occasionally. This is my wife's car and most of the time is still standing, we bought it because we like the shape :-) I think that 2" modification on the suspension in the car that will be used for Weekend trip outside the town will not damage significantly the wheel's hubs or axles.
Car is now equipped with 215/50/17 GoodYear Vector 4Seasons tires which outside diameter is 646,48 mm (25,45") so I got about 20 mm (3/4") to reach 26,3". If rubber coil inserts satisfy me, then I will think about changing tires to more offroad one but gaining 10 mm ground clearance by changing tires does not seem to be worth of it.
I will inform you about results.