I decided Im going to try this next week and will update then
Im going to put 17" rims with 235 55 17 tires on. it will add about an inch overall in diameter from the stock tires.
I know those tires are a big jump in size, so Im not sure what will happen and I am a little concerned about the power steering having difficulties but I already have the tires in my storage (I was going to use them on my truck but ended up selling it for the HHR) rims are supposed to arrive later this week.

 

Uhh. You're fixing to make a big mistake.
235/55/17's will NOT fit on a HHR. Those spec out to about 27.2 inches tall and will rub on the lower strut perch. In fact, I don't think you'll get the rims all the way on the studs with those tires.
26.2. maybe 26.3 inches is the tallest tire that will fit.

 

I didnt consider the strut tower, Ill look at it, not doubting you, just one of those things I have to see for myself :)
I can get smaller tires, was just hoping I could get away with these tires since they cost me $740.0 and never got used :/

 

If you could put taller tires on it, it will throw off you speedo readings also. Your ECM is programed for a certain tire height too.

 

Im ok with that, Im actually used to it.

 

Onlin tire stores have calculators.

 

I measured the tires (they are currently installed on rims, but for a nissan truck)
anyways, they measure 26.5" diameter.
sooo close, I am going to see what I can figure out to use these if I can.
the rims Im getting are a +42 offset, so they should actually sit 1mm closer to strut over stock 16" (+41 offset according to https://www.wheel-size.com/size/chevrolet/hhr/2008/ )
I "might" look into 3mm spacers if, and only if, they would allow the tires enough clearance of the struts. I really dont want to go that route, but Ive used generic spacers before with no issues so Im not against it.
measuring from the ground to top of fender well was exactly 27" F/R so even taking into account the slight raising of the vehicle to probably 27.25 with these tires on, Im not sure how close these would end up to the fender and I really dont want any rubbing (obviously) I also wont roll my fenders.
so there are a lot of considerations

BTW, just thinking out loud here :)

I use this site for comparison
​​​​​​​https://tiresize.com/calculator/

 

 

Exactly. And a 3mm (approx 1/8 inch) spacer isn't going to help much in getting the tire off the strut. Over the years I've seen a lot of folks "think" they can get oversized tires on a HHR. Don't remember any one successful at this without some dangerous 1 inch or bigger spacers. (something I would not recommend)

 

Did you check the fluid level as suggested back in post #72?

and you really need to reread Donbrew's posts - like he says, a 27.2" tire will NOT fit which is what your 235/55/17 tires officially measure out at.