I am hoping that someone has an idea on what is wrong...here are the facts:

New rear tires worn at a strong taper...to the threads...in $5k miles.
Viewing the car from the rear shows obvious strong negative camber on
both rear wheels consistent with the dramatic tapered wear pattern.
One shop looked at it and had no idea what was wrong.

For safety, replaced rear tires and took car to original dealer (somewhat
far away). They realigned the car and said that the camber and toe
measured out correctly on the rear end...with only minor adjusting needed
to make it perfect.

No sign of negative camber (even immediately after replacement tires were
installed).

Now, a few thousand miles later....both rear tires are worn in an even taper from the outside to the inside. With the insides being almost to the threads.

So...assuming this must be suspension related in some way for the camber to be corrected (temporarily) by putting on properly squared tires. Is this a failure of the rear self-leveling shocks? i suggested this to the dealer and they said the shocks were fine.

Thanks for your help!!

 

Ive seen this Once before......

Now....Before we go any further...PLEASE TELL ME YOU ARENT ONE OF THOSE PEOPLE.......

Who refused to replace the 19 inch tires because they were too expensive, and opted to buy 17 inch AFTERMARKET wheels and tires instead????

Typically, Leveling shocks wont cause this IF they are working properly......To cause your issue, the vehicle would have to jack itself to the sky in the rear, all by itself. If the vehicle "STANCE" is acceptable, you may rule out a shock issue.

 

Nope, not one of THOSE people. Original 19s and appropriate factory original sized tires.

It is hard to say if the car is sitting lower than normal. But, it is not
obviously tilted either way (seems same height on both sides). Is there an easy measure for rear ride height?

Thanks!!

 

I would be looking for too High....

Make sure you alignment was done with the correct tire options selected.

 

I can only assume that it was aligned correctly. The problem maintained
through four alignments, two at a tire store, one at a local shop and one at the dealership.

Alignment seemed fine in terms of driving "feel" with the fresh tires installed.

I have not been able to find any reference on rear ride height measurements. Where to measure and how high off the ground it should be. Any advice there?

Any idea what could be happening if ride height is correct? I can say that the ride height definitely does not seem higher than normal. It might be lower, but I am fairly certain it is not higher.

Thanks!

 

Djinn-n-Tonic,

I was thinking of doing just that, not just for the cost, but the LOUSY selection of 19's and for a more comfortable ride, what's the issue, are you saying this will cause tire wear?

 

The camber angle starts at the center of the wheel. the further out you go, the larger the difference in angle. I know in theory, that you align the vehicle and not the tires, But any change in height, changes the "Contact Patch" or "Footprint" of the tire.

Typically, going to a smaller diameter, will also make the tire "Thinner" , with less of a Footprint from the Much wider 19" s.

I dont know who told you that the smaller tire gives you an improvement in ride comfort, But he should be shot in the head with a lug nut. Absolutely not true.

 

Hey Djinn..

by no means arguing with you on swapping the 19's for 17's. With that said, do you know what components are different on a Pacifica that comes off the line with 17's vs. 19's? I have often wondered as most of the touring's had 17's, but some had 19's, the Limited all had 19's etc. yet are essentially the same car. And what would you expect to go wrong if, for instance I bought some OEM 17" rims and tires and stuck them on my Limited?

Thanks for the discussion.

 

I don't know where you're getting your facts
1.)"the larger the difference in angle" The angle doesn't change. If you set the camber to +1 degree And you go out 12 inches it's 1 degree, you go out 12 feet its still 1 degree, elementary trigonometry, the side opposite grows as diameter grows, not the angle.




2.) "Typically, going to a smaller diameter, will also make the tire "Thinner" , with less of a Footprint from the Much wider 19" s" well, if you size them correctly that's not true. The pac, at least my year 2007, came with either P235/65R-17 tires which are 7.5 inches wide & P235/55R-19 tires which are also7.5 inches wide. Both tires have the same outside diameter (+/- 1%).

3.)"I dont know who told you that the smaller tire gives you an improvement in ride comfort, But he should be shot in the head with a lug nut. Absolutely not true."
I told me that. When I bought my Pac, I road tested ones with both 17's & 19's. The 17's gave a smoother ride, the 19's gave better handling. 19 in tires are NOT smaller, just a different aspect ratio as stated above they both are the same outer diameter but the 17's have a larger sidewall, giving more "cushion" and the 19's smaller sidewall give a stiffer ride (which gives better cornering at higher speeds)

If you doubt my dimensions check both sizes here:

http://www.miata.net/garage/tirecalc.html

 

Yes....ok, I got your point....Technically 1 degree is one degree.

Now that one degree at 1 inch from centrline is 1 inch, The further you move out from centerline, the greater the "GAP" that is formed by the same 1 degree angle.....

Change the height of the tire, That same one degree angle , affects the Placement of The Tread Patch on the road. That is why both "Bear" and "Hunter" equipment make you specify tire size on a vehicle with more than one option. And incase you didnt know, Michellin tires are typically "Taller" than Identical sizes in a different brand. This can vary up to 4 %

Now, I am not one to say I told You so, And The only time I have ever "Gloated" is when the "Saints " won the superbowl.
You are free to do as you please with your car, Because it is your car....I just try to pass on my experiences......Take it or not....