rlb

I have a 2012 G37xS sedan that I just bought used. It has 21,000 miles on the original tires. No accidents. The car drives straight even when hitting the brakes. But, all 4 tires have noticeable increased wear on the inner shoulders. Otherwise the wear is even. Is this an alignment issue? Camber? What is adjustable when they do an alignment? The car is completely stock.

slartibartfast

iTrader: (7)

Is this an alignment issue? Yes
Camber? No, toe
What is adjustable when they do an alignment? Front is toe only. Rear can adjust camber and toe.

JSolo

iTrader: (14)

^^Why wouldn't excessive camber cause this type of uneven wear?

slartibartfast

iTrader: (7)

Gosh, I need to write up the toilet paper roll experiment to to illustrate why camber is not an issue. Maybe I can find it with Google...

I can't find the old visual tool. But the gist is to take a roll of toilet paper on an axle of some sort that allows attitude changes of the roll to the ground.

Lay it flat and roll perpendicular to the axle -- no visible wear. Toe and camber = zero.

Apply a small angle to the axle and roll in the original direction such that the entire roll surface touches the ground -- you'll see the paper exhibits wear and maybe some paper is ground off but the wear is even. Zero camber but +- toe.

Tilt one end up and roll perpendicular to the axle -- slight wear on the paper touching the ground. Camber +- but toe = zero.

Last condition is to tilt the roll and angle axle to direction of roll -- camber +- and toe +-. You see the greatest wear on the toilet paper at this condition.

JSolo

iTrader: (14)

Good animation showing camber - .

Unless I'm missing something, excessive negative camber will cause inside tire wear.

slartibartfast

iTrader: (7)

Not to the extent of toe. Trust me. Or not and Google alignment and tire wear.

blnewt

iTrader: (13)

It's possible the previous owner lowered the suspension, drove it without camber/toe kits then returned it back to stock to trade it in, this would account for the poor inner tread wear while the car still drives ok.

JSolo

iTrader: (14)

I see, so what you're saying is excessive toe will exasperate shoulder wear where as camber will be more progressive across the entire tread?

rlb

I thought toe in would cause more of a feathering? I don't think the previous owner lowered it but there is no way to be sure. Should I get the alignment done at Infiniti/Nissan or will I be ok going somewhere else?

slartibartfast

iTrader: (7)

Well, no one can align for a camber issue as front camber is fixed unless you buy and install adjustable front upper control arms. Only toe is adjustable up front. Infiniti is as good as anyone else, though searching out a shop that can give "performance" alignments is better as they'll deviate from OEM specs if you ask.

blnewt

iTrader: (13)

Since you stated that all four tires had heavy inner tread wear it sounds like it may have been lowered previously. If it was only one tire or a pair of tires then something out of align on a stock suspension sounds reasonable, but all four seems likely that it was dropped. There's plenty on this site that lower their cars and return them to stock on a lease return or trade in.

rlb

There is still some tread but I'm going to replace all 4 tires within the next month. I'll get an alignment when the new tires are mounted/balanced. Is there any way to tell if it was lowered? I can ask the place who does the alignment to look for signs.

blnewt

iTrader: (13)

You may be able to tell if your stock shock nuts have been removed if they're a bit rounded on the edges perhaps, or that area appears to have had some attention compared to the rest of your engine bay, but that's kind of grasping at straws. Your underside of your Y-pipe may be scraped up, but again, hard to prove that being lowered is what caused it.
When you get it aligned they should give you a before & after setting sheet. If the before alignment is ok, and no adjustment needed then I would say that it was previously lowered, but again, it may have been realigned at the dealer if they noticed the tire wear so

rlb

Thanks all for the replies. I guess I'll get the alignment checked when I put on new tires and report back the results. On a side note, my steering wheel shakes and vibrates a lot when hard braking from higher speeds. The car only has 21,000 miles and the pads have a good amount remaining. I'm guessing it is "warped rotors"(ie. uneven deposits on the rotors). I was going to get the rotors resurfaced to even them out. I've read it is best to use an on car lathe. Is this correct? Do I need to get new pads if I have the rotors resurfaced?

blnewt

iTrader: (13)

0
Try a few hard slow downs from 60mph down to 10mph, about 5-6x while never letting the car fully stop, this may clean some high spots if it is just pad deposits.

And one other thing, the lower front shock mount bolt (the big 19mm one) IIRC has a paint swab across it, so if it's ever been loosened you should be able to tell.
G/L