20 inches wheels for 1971 Buick riviera

Discussion in 'The Hides' started by Ammar737, Oct 4, 2019.

  1. Ammar737

    Ammar737 Member

    Hello guys,
    Kindly can I get the wheels specification for my 1971 Buick riviera, i am looking for 20 inches and i want to know what should the width of the wheels and what is the back space please

    Thanks alot
  2. gstewart

    gstewart Well-Known Member

    Why 20's?
  3. Electra Bob

    Electra Bob Well-Known Member

    Big wheels (I use 18" but would not go larger) are not my thing but scroll down on this page to get a complete list of sizes.


    Where it says "Wide tire" you might run into body fouling issues.
    The only 20" not to have this warning is:

    Rim size (in): 20
    Alternate tire size: 245/45 R 20
    Total wheel diameter (mm / in): 728 / 28.7
    Percentage diameter difference to the original (%): 1​

  4. Ammar737

    Ammar737 Member

    Ok sir , what is the OFFSET or BACKSPACING?
  5. Ammar737

    Ammar737 Member

    What is the OFFSET
  6. Electra Bob

    Electra Bob Well-Known Member

    I can't advise on that as every car is different. Even though I used a wider wheel I used the same stock back spacing.

    There will be a ton of folk on here that have used bigger wheels on a '71 Riviera who could give you first hand knowledge. I suggest starting a new thread asking about backspacing.

  7. silly

    silly Well-Known Member

    I might b a little late but i had a 68 buick riviera.. I had 22's on it for 3 years then in 2012 i put 26's on it.

    For the 22's they fit right on with no issues. Using 255 30 22 tires and the offset was 13+

    Now the 26's also fit on but i had to use spacers in the rear so they wouldnt rub in the back.

    I used 255 30 26 tires and only had to trim the inner wheel well in the front and had stock suspension the entire time i owned the car. The offset for the 26's were also 13+..

    So in other words just make sure your 20s offset are 13+ and you will have no issues
  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    First, it doesn't matter whether you wheels are 13" or 20", back spacing requirements depend on the width of the wheel. The back spacing requirement would be the same for a 13 X 7 as it would be for a 20 X 7.

    The 1971 Riviera used the big car bolt pattern of 5 X 5 bolt circle. From 1980 through 1987, there was a 15 X 7 Big car Buick chrome Rallye wheel. It had 4 1/4" back spacing. An 8" wheel would need 1/2" more, 4 3/4", 9" wheel, 5 1/4", and so on. This is theoretical back spacing to keep the wheel centered as stock in the wheel well.

    Second, and this is a pet peeve of mine:)back spacing and offset are two different measurements. Back spacing is measured from the rear edge of a rim down to the mounting surface of the wheel. Offset is measured from the center of the rim width to the mounting surface. The rim width if measured edge to edge is actually 1" more than the advertised rim width. That is because the advertised rim width is measured from one bead surface to the other. The center of a 7" wide rim is therefore 4" from either edge. The center of an 8" wide rim is 4 1/2". Offset is measured from the rim center to the mounting surface. In addition, offset can be + or -. Positive offset moves the tire/wheel in towards the center line of the car, negative offset moves the tire wheel out. Back spacing is a lot easier to measure.
    OldDrummer55 and RoseBud68 like this.

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