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mtn

1963 custom wheel question

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Ok guys I'm getting ready to order my wheels and I have some questions. Will a 15x7 wheel with a 5x5 bolt circle and a -12 offset with 3 1/2" backspace and center hole 3 1/4" work if I use a 1/4" wheel spacer on a 1963 Riviera ? I am ordering Allied Wheel Supreme wheels and want to be sure they are going to fit. I know I will need the spacer because the center hole is only 3 1/4 and also because of the rivets on the drum but I only want to do this once !! Any help or guidance is appreciated.

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15x7 with a quarter inch spacer ~ OK.

3 1/2" Backspacing ~ OK.

5 on 5 Bolt Circle ~ OK.

What is the -12 offset? Don't understand that part.

Don't forget the lug nuts. Unless these have been changed out, your 63 will have left hand thread lug bolts on the driver's side. Here is a related thread;

http://forums.aaca.org/f177/left-hand-thread-lug-nuts-300610.html

Good luck. These look real good on a Riviera.

post-53315-143138912907_thumb.jpg

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Thanks Steelman. I also have no idea what the -12 offset is but it was shown in the specs for the wheel?

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They don't explain what the -12 offset is on their website, either. Should be OK. You will also need the 1/4" spacer on the rear, due to the large axle hub to get the wheel to seat. Get 4 of these when you get them.

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Negative offset is expressed in mm and describes where the bolt face of the wheel sets in relationship to the center line of the wheel. Negative offset means the bolt surface is 12 mm toward the brake side of the wheel in relationship to the center line of the wheel.

Wheels for front wheel drive vehicles have a very large postive offset - it looks like the lug nuts are on the same plane as the face of the rim.

wheel-offset-backspace.gif

Ed

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If the backspacing is right, dont worry about the offset.

Backspace and offset both give you the location of the wheel mounting face, but they are measured differently, by using two different points of reference.

Lets start of by choosing a wheel, say 17x8. The 8 part is the "bead" width so to speak, the inner distance between the front and rear wheel lips, where the tire would mount.

Now if you put that same 8" wide wheel flat on the ground and measured from the floor, to the outer edge, it would = 9", the 8" bead width, plus 1/2" front and back for the wheel lip.

Ok backspace measurement - this is the measurement from the hub mounting face, to the outer edge of the lip at the back of the wheel (the 9” width)

Offset, is the distance (in MM’s) the hub mounting face is moved from the center line of the wheel, forwards or backwards, using the bead width as the total width (the 8” width) .

So an 8” wide wheel, with 4” backspace (so would have 5” dish), but it will have -11 offset (the mounting face is moved ½” rearward of the wheel center line)

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Thanks for the explanation guys. I'm planing on ordering my wheels this week so this has been very helpful. These wheels are uni-lug I found out yesterday but that should not make a difference right ? Ed, I still owe you a beer and some dinner!!

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Anytime you're in the neighborhood I'll be both hungry and thirsty. I went to the Car Quest store shortly after our last encounter and bought another water pump just for good measure. Both the counter guy and I agreed that it was a new, not rebuilt pump. 5 impellers. Good item to have for one of those moments.

Ed

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Thanks for the explanation guys. I'm planing on ordering my wheels this week so this has been very helpful. These wheels are uni-lug I found out yesterday but that should not make a difference right ? Ed, I still owe you a beer and some dinner!!

Unilug means just that. Covers more than one bolt pattern. Instead of round holes in the wheels for the lug studs, you have slots. Wheel manufacturers have been doing this for years. Just need to be sure when your lug bolts are installed, you use the loose thick chrome washers when you install these. Important to use these washers on a unilug wheel.

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Here is a picture of a Cragar type unilug washer. Cragar's are round, some other mfg's. are oval. For 4-3/4" bolt circles, you use the washer where the hole is in the center; for 4-1/2" bolt circles, you use the off-center washer with the hole toward the hub; for 5" bolt circles you use the same off-center washer but with the hole toward the tire.

cragar_washers.jpg

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