Sorry for the long post. I'm trying to decide if I need to order one or two alignment shim kits before bringing the car for an alignment.

I bought a 2016 GT S few months ago with 16K miles. It is lowered on H&R springs and has 20/21 inch wheels. I think the tires have about 8 to 10K miles on them. I looked at the tread when I got the car and was expecting to get another 5K miles out of the rear tires. I noticed uneven wear on the inside, but nothing too concerning. I put about 2K miles on it so far. Just some occasional spirited drives, no drifting or anything crazy. Two weeks ago I noticed that inside of the rear tires shredded badly. Passenger side is the worst. I ordered new tires and it is obvious that an alignment is needed.

I contacted previous owner and he says it had two alignments done. First when the wheels were installed and second time when it was lowered. Both times done by good shops. He says, "I wouldn't touch it, but that's my 2 cents. It was adjusted to ensure the fitment doesn't rub and close to factory specs."

Does it mean the alignment that's on the car allows larger wheels to fit inside wheel wells, but wears tires unevenly and I have to deal with it or can the toe or camber be adjusted to reduce the wear?

I don't know the current specs and planning to bring to a shop, but what I'm not sure is if I need to order one or two (?) shim kits before I bring it in for an alignment. Or should I bring it in first, see what's off and and then order the shim kits. .. how many ever needed?



There are few previous posts regarding alignment, but it is still not clear to me if I need alignment shims or not. Some excerpts from previous posts. =============================================
1.I went from -2.9 rear to -2.2. I picked up another inch of rear contact patch.

2.Looks like kumizie, one of the members did not need shims as his was lowered 3/4th inch and was set to - 2.5 in the front and - 2.2 in the rear.

3.From another threadFind a great alignment shop locally and have it checked prior to spending big money on the OEM shims you might not need.

 

There are not multiples of each shim. Just enough of each for one side in multiple degrees. Hope that makes sense

I left my front alone. I adjusted my rear from -2.1 to -1.5 or so. I track and wanted the bigger contact patch and I also went to 325/30/20 sport cup 2

 

​​​​​​That makes sense! Is this the right part number 197-357-06-00?

I have 325/25/21 in the rear. Fronts are wearing evenly and no issues.

 

I would pay to have the alignment inspected as to current settings before you spend the money buying shims as they aren’t cheap. The toe on the rears could be incorrect causing that uneven wear.

 

I'm taking it to a shop tomorrow to have the current specs checked. That's what the shop suggested as well. Check first before spending money on shims.

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