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Wear across a tire lug

  1. Mar 11, 2014 #1

    I have some basic questions about tire surfaces..specifically the lugs and I wonder if anyone can help. They are:

    1) On a new tire, are the lugs flat?
    2) On a worn tire, are the lugs flat?

    I understand there are a variety of different tire wear conditions that can affect the tire both circumferentially and latitudinally. But I'm specifically asking about wear across the lug surface.

    Thank you!
  2. jcsd
  3. Mar 11, 2014 #2


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    It's not clear what you are referring to here. Tire lugs and lug nuts are what secure the wheel and tire assembly to the axle of a car. If properly secured, there should be no wear to the lugs, i.e., the lugs should last the life of the car.

    If you are referring to something about the tire that wears, perhaps a more detailed description could provide greater clarity.
  4. Mar 11, 2014 #3
    Across the face of the lug, it is possible for some lugs to be flat or wear flat, but in general they will have a rounded surface circumferentially. Of course, the contact patch will be pretty flat. Bad shocks or suspension parts may cause odd patterns, but I wouldn't expect a truely flat surface, although an exception may crop up if the lug is small enough. Why would you expect a rolling tire to create a flat lug?

    Steamking, I believe the OP is referring to the tire tread as lugs. Off-road tires in particular refer to lugs.
  5. Mar 11, 2014 #4


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    Thanks for the clarification, Highspeed.

    Gvalch - like Highspeed said, unusual wear patterns on the surface of the tire, like flat spots, are indications of problems in the suspension of the vehicle, like shock absorbers which no longer function, or mis-alignment or wear in suspension components.
  6. Mar 11, 2014 #5

    Ranger Mike

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    Non round tires are common. The rule of thumb is 0.030" run out on the tread. Production tires are not to good off the tire mold to begin with.
    The biggest problem with tire wear is improper inflation. I won may a $ 100 bet with bar flies in the bar that I could not find ten cars in the parking lot with under inflated tires. Same with proper engine oil levels but that is another story.
    check out attached photo.
    Tire balance is the second biggest problem and can cut the tires until they flat spot.

    Add to this the typical McPherson strut front suspension and road surfaces with lots of pot holes and the steering alignment goes pretty quick. Same on t he rear with poor quality suspension on low end vehicles.
    Alignment- Castor , camber and toe in should be maintained to factory specifications. When ball joints and tie rod ends wear you have a pulsation compounded by up and down movement of the spring/ shock (damper) assembly.

    One big cause of flat spots is locking the brakes up and skidding to a stop usually under panic conditions. Once the tire is flat spotted it only gets worse with wear.

    Attached Files:

  7. Mar 12, 2014 #6
    Thanks for the help!

  8. Apr 1, 2014 #7
    Most passenger tires have a tread depth of 9 to 13 16ths of an inch, consistently from side to side. If inflated to the correct pressure and mounted on an aligned vehicle, the tire should wear evenly.
  9. Apr 1, 2014 #8

    Ranger Mike

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    and properly balanced...
  10. Apr 1, 2014 #9
    How would a tire wear on an unbalanced wheel? Would it be similar to a tire mounted to a bent wheel?
  11. Apr 1, 2014 #10

    Ranger Mike

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    out of balance condition is probably the biggest cause of tire wear followed by under inflation or close to it..i would probably put under inflation as number one but they are the two main reasons..it really takes a lot to wad up front end components to mess up camber or toe in...
    pot holes can bend a rim but it really takes a lot to do it and you darn sure know when you got a bent rim..same with out of balance..under inflation usually has tell tale symptom of pulling to one side...
    out of balance causes wear, if you think about it ..by causing the tire to rotate both axially and radially versus tracking " straight forward" as in the case of balanced tire. Causes the tire to shimmy and ' squirm" back and forth as well as rotating in the direction of travel. This scrubbing action causes excessive tire wear in the most unbalanced tire area and this wears this portion of the tire excessively more than the other tread portion and scallops the tire. see attached pic in my post above
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