IRS rear tire wear

[Mud]

Is this just part of living with IRS? Our 2008 Accord is aligned about twice a year as part of regular maintenance, yet since day 1 it likes to wear the inside edge of the rear tires. It is never overloaded, usually 1-2 passengers and a full tank is about it, yet it seems that the factory settings for negative rear camber are the root cause.
I know just looking at the car is no indicator, but I can see a very slight negative camber with a full load of fuel so I'm sure that in most cases as the suspension articulates going down the road the condition increases.
I'm not sure if the rear camber is adjustable? I looked online but what I generally find are replacement camber kits for cars with lowered suspensions. Our car is bone stock down to the tire size.
I understand the reasons that the factory sets for negative rear camber but its seems that a bit could be safely dialed out. Just wanted to ask some of the alignment experts here before I take it in for an alignment check.

 

[eljefino]

Look around parking lots particularly at mazda 3s this camber thing is everywhere.

 

[SteveSRT8]

This is a common complaint nowadays due to IRS and wear and tear.

If you haven't done so take a look at the inside edge of your rear tires on any IRS vehicle. You may be surprised.

BTW, I would be almost positive it's adjustable, but you may not like what it does to the handling...

 

[Eddie]

If the alignment is good according to the factory specs then I would probably do a front cross & rear to rear same side rotation every 5-7K miles to even out the wear. I agree with SteveSR that if you adjust to far from factory, the handeling may suffer. Ed

 

[Hokiefyd]

It is adjustable, but requires an adjustable upper link to do it. It's not adjustable as it sits now, unless a kit has already been installed. It's likely sitting a bit lower than what it originally did due to springs settling, etc. I installed the adjustable links on our MDX when we first got it to correct a fairly pronounced rear camber issue.

Here is a closeup of that upper link.

Our CR-V still has the stock upper links, with about 1.5* of rear camber, and doesn't have any inner tire wear. What is your actual rear camber measurement? Sure it's not something like rear toe intead? To my understanding, rear toe plays a greater part in rear tire wear than does rear camber.

 

[ARCOgraphite]

Another reason why IRS is not need or wanted on non-driven rear wheels. Wish manuf would put the money into a nice NON STRUT front suspension instead. Mac struts are garbage - the weakest link by far on my old 98 BMW M-roadster.

 

[Mud]

Great info, thank you. Yes, I've seen a number of cars with similar, it seems that a lot of BMW's in particular exhibit this, at least to my eyes.
Forgot to mention that tires are balanced and rotated every 5000 miles. The current set of tires are directional so they can only be rotated F-R, I don't plan to install any more directional tires as I prefer the cross-rotation.
Hokiefyd, nope, no kit has been installed but that's a great pic, I think the Honda version that I've seen is about the same. I cann't say for sure about the rear toe vs camber, but that is a good question to follow up on. I do think its more of a camber related issue simply from observation of how the car sits but that's just a guess.
I found that the rear arm is not adjustable but there is a fairly straightforward install of an adjustable kit if desired:
http://www.driveaccord.net/forums/showthread.php?t=30111

I understand that rear negative camber is preferred for handling as it tends to induce understeer rather than oversteer. Spec range is -1.8 to -0.5 camber for the rears. I think that my last alignment was -1.5, but it seems reasonable that I could consider the installation of the adjustable kit and reduce the neg camber to 1.0, still within factory recommendations?

 

[Cujet]

If you have an iPhone, you can easily measure the negative camber using any number of "free" level apps.

A really quick and dirty way to measure it: Load car normally and drive car on to 4 newspapers. Bounce and shake it a bit. Then measure using your iPhone app. You can try the tire sidewalls, but the rim's edge is better. Take a number of readings, with your well calibrated phone. Use both sides of the phone and average the readings.

Look up the specs and see if you are close.

I suspect you have too much negative camber and adjusting it towards zero will help your wear problem. And, since modern cars understeer excessively, you won't be at much risk of oversteer. Especially if you keep it within the adjustment range.

 

[Gotch]

Rear camber is not adjustable on the stock upper arms. As posted above, you can get a kit if it is really something you want adjusted. Toe, from what I understand, is adjustable. I had the same issue with my 06 Civic which was repaired under warranty under a TSB. After my repair, turn in was improved and I could actually get a bit of lift throttle oversteer (not enough to skid). I went plus zero on my tire size, from 205/55/16 to 225/50/16 so the tire wear in my case was very bad.

If you are looking to upgrade your wheels and or tires, the adjustable upper arms will be needed anyways.

 

[Hokiefyd]

Originally Posted By: ARCOgraphite
Another reason why IRS is not need or wanted on non-driven rear wheels. Wish manuf would put the money into a nice NON STRUT front suspension instead. Mac struts are garbage - the weakest link by far on my old 98 BMW M-roadster.


To my knowledge, his Accord already has a nice non-strut front suspension. The Accord still uses a double wishbone front suspension. I've owned non-IRS cars and prefer IRS every day of the week.

 

[HerrStig]

Originally Posted By: ARCOgraphite
Another reason why IRS is not need or wanted on non-driven rear wheels. Wish manuf would put the money into a nice NON STRUT front suspension instead. Mac struts are garbage - the weakest link by far on my old 98 BMW M-roadster.


I used to change the front shocks on my Volvo 140s (last of the non-strut front ends) without even jacking the car up. I may buy a Accord next time in part BECAUSE they use wishbones instead of struts on the Accord.

 

[TylerL]

Mud, if you want you can safely running your directional tires in the wrong direction. According to bitog's resident tire engineer (Capriracer) the only downside is about a 10% decrease in wet traction.

Tirerack test:
Lap time with Eagle F1 GS-D3
Mounted correctly on a dry track: 29.387 seconds
Mounted backward on a dry track: 29.465 seconds - 0.26% slower

Mounted correctly on a wet track: 30.373 seconds
Mounted backward on a wet track: 30.387 seconds - 0.05% slower

 

[CapriRacer]

It has been my experience that ANY camber over 1º tends to cause tire wear on the inside shoulder - and toe acts like a multiplier.

Further, this also tends to wear the tire in an irregular pattern - commonly called "cupping".

So while the camber really improves the handling, the tire becomes worse. Take your pick!

 

[SwampSurvivor]

Reason I hate IRS.

Now that my jeep is aligned correctly, the tires wear like iron

 

[Mud]

Originally Posted By: CapriRacer
It has been my experience that ANY camber over 1º tends to cause tire wear on the inside shoulder - and toe acts like a multiplier.

Further, this also tends to wear the tire in an irregular pattern - commonly called "cupping".

So while the camber really improves the handling, the tire becomes worse. Take your pick!


you have described the condition of the tires exactly - wear on the inside shoulder with cupping in the tread bar right next to the worn shoulder.

Since I plan to keep the (paid-for) car

from what I've read it does seem that the installation of adjustable arms is a reasonable solution as long as I don't get crazy about positive camber.

I really appreciate the input. Thanks also for the info about the directional tires. I will admit to thinking they would self destruct if run opposite lol!

 

[Hokiefyd]

Originally Posted By: Mud
Since I plan to keep the (paid-for) car

from what I've read it does seem that the installation of adjustable arms is a reasonable solution as long as I don't get crazy about positive camber.


You won't want any positive camber. Just less negative camber. Shoot for as close to zero as the specification will allow. I have our MDX set up this way (it's about -0.5 deg), and there's zero irregular wear. That said, our CR-V is about -1.5 deg and there's no irregular wear there either.

Some tires wear differently than others as well. What brands of tires have you been using?

 

[TC]

Everything you ever needed to know about rear IRS issues was covered in "My Cousin Vinny."

 

[Mud]

LOL, I get that

Sorry, when I mentioned positive camber I should have said less negative camber. My game plan is to install the rear adjustable arms and ask the tech to set the rear negative camber as close to 0 or at least less than -1, which is still within factory spec.

 

[mechtech2]

Being an IRS should help, not hurt, tire wear.

Almost all FWD rear wheels are neg camber. And almost all are set for toe in -pigeon toed a bit. They splay out when driving to zero toe [ostensibly].
A little neg camber won't eat tires it is a good thing to have. But excessive toe will eat tires, and esp toe out like you seem to have from your described wear patters.

 

[artificialist]

I have dealt with certain vehicles where even if the alignment is within spec, the tires still wear abnormally.

Anyway, in my family there have been plenty of IRS suspensions on the Back of our FWD cars:
1985 Nissan Maxima: No abnormal tire wear patterns... Just rapid wear.
1992 Nissan Sentra: No abnormal tire wear problems.
1994 Eagle Summit: No abnormal tire wear
1995 Honda Accord: No abnormal tire wear
1997 Lexus ES300: No abnormal tire wear
1999 Honda CRV: No abnormal tire wear
2007 Pontiac G6: No abnormal tire wear.
It is too early to determine if my car will develop abnormal wear or not.