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what size are my stock rallys?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by EZdoesit, Oct 11, 2001.

  1. EZdoesit

    EZdoesit Registered Member

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    Hi everyone, this is my first post. I'm lifting my 87 Blazer 4", probably with a rough country lift and I am also buying a set of almost brand new 33x12.50-15 pro-comp ATs from a friend, I need to know how wide my stock 87 rally wheels are so I know if I can use the stock rims for this winter or order new wheels right away if I need to. thanks!
     
  2. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    They are 15x8 and they will work but your tires will wear out quicker in the center due to the tire being squeezed in.

    '85 K5 : Run it til it breaks, then fix it and go again!
     
  3. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    I have 35x12.50 on 15x8 's with no problems. I have used them for years. Never had a problem with center wear. Not that it could'nt happen but just my experience.

    John

    <font color=blue>"When all else fails, read the instructions, or get a bigger hammer"</font color=blue>
     
  4. EZdoesit

    EZdoesit Registered Member

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    Thanks for the info guys I appreciate it!
     
  5. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    Yeah, the extra height of the 35 helps offset the narrow rim, and reduces the tendency to make the tire bulge. I ran 33" BFG all terrains on rally's for years and the centers always wore out first.

    '85 K5 : Run it til it breaks, then fix it and go again!
     
  6. RedDwarf

    RedDwarf 1/2 ton status

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    That's because you ran too much pressure, not because the rims were too narrow.

    The rule is: keep the rim width within about an inch of TREAD width. Most 12.50" tires have a tred width of about 9", so 8-10 will work fine.

    I have talked to guys who ran 12.50"s on 7" inch rims. They say it works fine, but they were mostly trail rigs...

    Still Poundin' "pavment" after all these years!!! [​IMG]
     
  7. 6.2Blazer

    6.2Blazer 1/2 ton status

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    An 8" wide rim is actually just about right for a 12.50 tire. With the right air pressure in the tires, you should not have any problem with wearing the centers out (as already mentioned this problem is typically caused by running to high of pressure).
    Many years ago, I had 32x11.50's on 7" rims. They had over 25,000 miles on them when I sold them and had absolutely no signs of the center wearing prematurely.
     
  8. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    No I wasn't running too much air pressure. An 8" rim is too small for a 33x12.50. If you check with BFG on there reccomendations, they say atleast an 8.5" rim for their 12.5 tires. An 8" rim causes the tread to be bowed, not flat like it needs to be for even wear. I have a buddy that is running this exact combo right now, and even aired down to 24 psi they are still wearing faster in the center. In my opinion 24 psi isn't safe to be running on the street.

    '85 K5 : Run it til it breaks, then fix it and go again!
     
  9. K5Jimmy

    K5Jimmy 1/2 ton status

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    I run 33 AT on 8" for street and highway trips.....I got 46k on 'em now , and I'll be lookin' for another set prolly this Spring....they are evenly worn, as I rotate them about every 8k or so....I run 30lb.....I also have 33 BFG Muds on 10" Rallies...I think they look better on 10", but the wear is about the same....I run the Muds at about 32psi, and drop to about 26f/22r for Banzai runs down the black dirt county roads after it rains.......I think part of the wear factor is rotating, and inflation...the main thing is solid front end parts....

    Stuck?...Hell no..I still got some gas left..
     
  10. chevrules

    chevrules 1/2 ton status

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    An 8" rim is perfect for a 33x12.50 tire,just monitor the air pressure.

    chevrules...always has and always will
     
  11. RedDwarf

    RedDwarf 1/2 ton status

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    24psi in a 33x12.50 unsafe?

    What is your idea of a safe pressure to run???

    Still Poundin' "pavment" after all these years!!! [​IMG]
     
  12. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    Notice I said on the street. 24 is less than what BFG reccommends. On a rim that is too narrow it is less dangerous than on a rim that spreads the tire out. With low air pressure you run the risk of rolling the tire off of the rim when making sharp turns at speed. Not to mention the fact that an under-inflated tire will overheat and can cause tread separation. Just ask Explorer owners. In fact that is Firestones biggest defense is that Furd told Explorer owners to inflate their tires to 24 PSI which is below the manufacturers reccomendation which caused extreme heat and tread separation.

    '85 K5 : Run it til it breaks, then fix it and go again!
     
  13. RedDwarf

    RedDwarf 1/2 ton status

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    YOu do realize that as tire size increases you need less pressure to support the same weight don't you?

    Exploders use what 205-70-15?

    Still Poundin' "pavment" after all these years!!! [​IMG]
     
  14. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Thats odd.

    I have found from previous off roading excursions, that a wider rim will separate the tire from the bead easier and faster than a narrower rim, especially after airing down the tires.

    I have driven tires aired down to 25 psi on the streets and highways with no problems.

    The narrower the rims, the taller the tire. No tire will wear out faster than others if the rim is narrow. It all depends on the air pressure you have in them. If the tire shows wear in the middle of it, let some air out of the tire. If there is wear on the outsides of the tires, you need more air.

    I find it easy to get the proper amount of air by chalking a line across the tires contact patch, or treads. Drive around town for a couple miles and then get out and inspect the chalk lines. If there are some chalk lines left, that will show your "over-inflation". If the line is gone, you have the proper pressure.

    <font color=red>I'm a "black top mudder"!!!</font color=red>

    <a target="_blank" href=http://coloradok5.com/gallery/thatK30guy>The K30 Collection</a>
     
  15. chevrules

    chevrules 1/2 ton status

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    I agree 100% with you K30.I have also used the chalk method,it works.I run about 28 psi front and 25 psi rear all year.

    chevrules...always has and always will
     
  16. Mr.Chevy4x4

    Mr.Chevy4x4 1/2 ton status

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    And I suppose you think that a 14.5 tire could be run on a 8 inch rim with a correct wear pattern. NO! That is why the manufacturers have reccommended wheel widths. If it didn't matter then they wouldn't publish them. When you run a tire with a wide tread section on a narrow wheel you cause the tread to be arched, not flat. You obviously didn't read my post, because I said "On a rim that is too narrow it is less dangerous than on a rim that spreads the tire out." I understand this principal, but I also understand that there is a reason that there are wheel manufacturers that make 15x12 and 15x15 wheels. If tire pressure could fix any tread wear problem then why would anyone make wide wheels?

    '85 K5 : Run it til it breaks, then fix it and go again!
     

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