scalloping/feathering/?? tire wear 1

[Tmoose]

Our Mazda MPV minivan and older HOnda Accord have worn alternate tread blocks pretty severely on one edge. Driven wheels worse. Outside edge on the MAzda. Inside edge on the HOnda. The wear on individual tread blocks is greater at the forward (or is it rear?) edge as would be expected on a drive wheel. Noisy !! One shop changed the wheel bearing, claiming that was the problem on the Honda.

first, the tire websites seem to combine or even interchange feathering and scalloping.

http://w

http://www.falkentire.com/images/tire_damage/large/ohtsu_scallop_wear.jpg

http://www.monroe.com/support/Symptoms/Tire-Wear

Second, Is there a real solid individual cause for this type of wear? These cars both have original struts/shocks that still seem very functional and ball joints that measure very acceptable, and fairly regular "alignments."

 

[CapriRacer]

First, feather edge wear is a normal wear condition. It is caused by the fact that as an indiviudal tread element enters the footprint, it is pushed back and the leading edge gets rounded.

When the tread element leaves the footprint, it holds on until the friction is overcome and it snaps our of the footprint, leaving a little "feather" on the trailing edge. This is commonly called "Heel and Toe" wear because the result looks a bit like a human foot.

This type of wear can be aggravated by mis-alignment - toe in particular. Keep in mind that the ideal alignment condition is for the tire to be pointed straight ahead in the dynamic (rolling) mode, any deviation from straight ahead causes a slight angular force across the face of the tread, accellerating the wear rate. That means that even toe-in values "Within Tolerance" can cause the condition to be more severe.

But toe-in also aggravtes other tire wear conditions. "Scalloped Wear", "Cupping Wear", and "Diagonal Wear" can literally all be thrown into the same bucket as they are either different ways of expressing the same type of wear. Personally, I like to use the term "Irregular Wear".

Yes, shocks can contribute to these conditions, but my experience says that alignment plays a larger role.

The fact that your cars are wearing different edges would point to difference in alignment as contributing to the conditions.

How to fix? Without more details, it's hard to be precise. Part of the problem is with the alignment specs themselves. It is pretty common for alignment specs as published by vehicle manufacturers to have pretty wide tolerances - wider than they should be to assure good tire wear.

Further, some vehicle manufacturers have alignment settings that produce good handling, but aggravate wear conditions. Camber is one such setting. I've found that anything over a degree tends to generate such wear.

But part of the problem may be such simple things as rotation and inflation pressure. Once an unusual wear pattern starts, it is very difficult to "erase" that pattern. The best practice is to rotate regularly to prevent those types of wear patterns from developing too far that they can not be undone by the wear pattern generated in another wheel position.

So I would get an alignment and insist that all alignment values be within the inner half of the spec.

Second, before you get the alignment, find out what the values are supposed to be - including the tolerances. In order to help quantify when the target values are too high, I've come up with some "Idealized" settings:

http://www.barrystiretech.com/alignmentrecommendation.html

Unfortunately, once such wear starts, it's too late to see if the corrected alignment fixes the problem. What happens is that the wear just proceeds more slowly. You can't gauge whether or not the corrected alignment prevents the problem without also starting with new tires.

Aggravating the alignbment problem is that most alignment techs don't have enough theory to know when the alignment specs are at fault - so they blindly follow the published specs. So it becomes important to do your homework on the alignment settings first, then find an alignment tech who will follow YOUR desires, and not what is published.

 

[NormPeterson]

I think we need to know a little more about the way these vehicles are being driven - how hard and how abruptly are the various maneuvers being made - in addition to knowing what the alignment specs actually are.

For example, I would expect the outer shoulders to generally get beat up a little more on the MPV if it is being driven more "enthusiastically" around corners than was expected or intended by Mazda. Ditto for the Honda inside shoulders if hard braking is frequently required.

Worn dampers would exaggerate those tendencies by permitting the vehicle to "overshoot" the equilibrium roll or pitch angles and driving the instantaneous cambers even further away from optimum. But I wouldn't expect this to be the root cause.


Capri - what sort of frequency would be assocoated with alternate tread block wear and could it unfortunately coincide with some tire mode?


Norm

 

[evelrod]

Without going all technical, the first actual question was "is there a real solid cause...". Yep. You bet. Lack of proper maintenance from long service or accident/mechanical failure.

From your photo, incorrect camber and out of balance tire along with a high probability of under inflation.

Put the suspension settings back to OEM, keep the tires balanced and properly rotated...Problems will go away.

This is not wear from high performance driving. It's just abnormal wear from 'regular' driving. This is the stuff I see on my daughters tires when she still cannot find time to stop by my race sponsors tire shop...where they keep up her crap for free, anyway.

Rod

 

[CapriRacer]

NormPeterson (Structural) said: "What sort of frequency would be assocoated with alternate tread block wear and could it unfortunately coincide with some tire mode?"

I can not remember exactly where I got this from, but there is a study that shows that irregular wear can be tied to higher order vibrational modes in tires. That's why it will show up as every other lug or every 3rd lug, or with other more unusual intervals, such as 2nd, 3rd, 3rd, 2nd.

 

[pennswoodsed]

If I were a betting man , I would wager that the front weight biased , primarily front braked,exclusively front steered and front drive in at least 50% of the vehicles in question have tire wear exactly as could be expected.
Evelrod's daughter's maintenance schedule is repeated by most vehicle operators. Tire rotation alone will at least spread wear evenly and increase total miles achieved.
Capriracer has a wealth of knowledge that few will ever apply.


Regards,Ed
Ps NormPeterson, interesting question,I will research if I remember to.

 

[rmw]

Always be suspicious of tire manufacturers information. I have seen some that are agregious with respect to making it seem that every conceivable problem is the customer's fault. And big names too.

Plenty are, and I would even say that probably most are the result of user abuse, but NOT ALL tire problems are user caused.

rmw

 

[cibachrome]

Look for an out-of-dynamic-balance condition (not static balance). Its already too late, though. Tire could be blems or pending tread sep.

Have someone drive the vehicles for you on a highway and go thru a speed range. Watch each tire and you will be surprized at what you see. If you have a strobe light, do the same experiment at night. It's always entertaining when yo can make your tires stop in place or slowly rotate backwards (after you locate the blem locations, of course).