what are the GM supplied wheel/tire sizes?
18"x ?.?"?
2??x??x18

and how many revolutions per mile?

i was looking at some michellins in the 18" for a set of rims i have my eye on and the michellin site went so far as to put how many revolutions per mile the tire has (this is important for the mph/mileage sensors etc etc) and also before i make any modifications to my HHR, im doing as much research as possible to see if anything i do could/would have a problem if said modification infringed on the warrenty. Since i have an LS and there is basicly NO dealer/gm options in terms of exterior addons such as rims/tires

what im researching is the differences in drivetrain components (transmission, cv joints/shafts, brake components, suspension parts etc) on my 2009 HHR Half Panel LS made full panel with back seats, since there are so many different options available for the various models (LS, 1LT, 2LT, LS panel, 1LT panel, 2LT panel, SS, SS panel)

so i guess what else im looking for is part #'s for the CV joints, suspension arms, brake callipers, pads, rotors, drums (obviously the SS has 4 wheel disk), shocks, springs

in order to compare these key components, then if all things being equal, there should be no reason why there would be any problem with putting 18" rims on an LS model if those above components were the same part #'s as the 2LT or the SS, now if the SS (the only model that offers 18" rims as an option) has a completely different part # and part all together for the cv joints, then if i put the 18" rims on my LS and the cv joints busted then i would obviously be at fault for exceeding the limitations of those shafts in the eyes of warrenty issues, but if they are the same and i use an 18" rim/tire package that the overall tire size at the tread is the same profile as the 16" model with the same revolutions per mile, and the same offset as the 16" steels, then the only major difference would be the accelleration/braking force needed to start/stop the oversized rim due to enertia


so if anyone has any information or resources to assist me, it would be greatly appreciated, i used the search on this forum for weeks now and i really am sick of seeing the steering wheel radio button control DIY mod ~_~ (though i do plan on using it ^_^)

 

you can put 18s on ur ls. just need to have the speedo adjusted for the larger tire

 

Depending on what size tire you go with it will not affect your speedo very much at all i have 2 set of 18 inch wheels one set has 40 series tires and the speedo is off by not even a half mph and my other set i have 45 series tires and its off by about a half mph.

 

Tire size info : two site to use. put is stock size and then the size you want and see if they are the same Dia to maintain a speedo that will be the same, other site will tell you how much your speedo is off by using different size tire. all this has been posted before but once in awhile newer member are not aware of them.
http://www.rims-n-tires.com/rt_specs.jsp
http://www.web-cars.com/math/tiresize.html

 

thanks for the input...

i dont plan on changing the overall diameter of the tire, so ultimately im just putting an 18" rim on the vehicle with new tires that would have less of a sidewall so basicly if the tread patterns were the same and you were looking at the two sets of tires mounted on the rims side to side and looking at them from the front you wouldnt be able to tell them apart

whats the GM 18" rims dimentions 18x7 with a 40mm offset? or 18x7.5 with a 42mm offset or ? thats the info i need along with the tire size such as 225x50x18z or? and if anyone knows what the stock 16" steel rims offset is would be greatly helpfull.

ive seen many sites and been through many catalogues that have the tollerance for the HHR's offset to be in the ballpark of 35-42mm would have an acceptable turning radius as to not have any rubbing issues, but for all things considered, i would like to remain with exact specs so if the issue arose i could say the new equipment fits exact tollerances

also the center bore would be nice to know as well

 

by the way, in my seach i found this nice lil applet:

http://www.andysautosport.com/rims/chevrolet_hhr.html

which tells you the OE tire size as P215/55/R16 with an OE diameter of 25.31" with a +/- tollerance of 3%

 

I recenlty went from the stock 215/55R16 with a set of Cobalt SS/SC 18's with 225/40R18's and side by side, they were almost identical in height. According to the charts, by speedo should be off less than .9%. No rubbing issues at all.

You should not have to change any other components.

 

well in my search for answers, i contacted GM directly... they said ANY GM branded rim that fits that falls within the specifications of dimentions for rims on the HHR will retain the warrenty fully...

SO if you happen to have 200 rims from various GM vehicles that just so happen to have the 5x110 lug pattern and an offset of 35-42mm upto 18" then you could put that on the vehicle (if i had enough i would put 4 different rims on there with the same dimentions and tires THEN take the vehicle in for service just to be a jerk after what ive been through with gm)

but what i dont understand is, GM never said anything about tire size!?!?!?!? just the dimentions of the rim... i personally think the tire dimentions are more important than the rim, all things being equal in fitment...