Anyone know the wheel offset of a "76 Eldo?

[Ross DeVore]

Anyone know the wheel offset of a 76 Eldo? I know the bolt pattern and rim width but dont have the correct offset number.
Anybody out there know it by chance?

[Steve Preston #16375]

The manual states 3.31 in. I believe thats negative 3.31.

[Rob Gerace #16100]

Im not sure what the real value is, but I wouldnt think that it would be that negative.  Negative 3.31 means that the mounting surface of the wheel is 3.31 toward the inside of the wheel, measured from the centerline of the wheels depth.  I think the car would look a bit skateboarded with such a negative offset.  I may be wrong, but it just sounds a bit wierd to me.  

Just a note:  Using wheels with a significantly different offset than the stock wheels, can make your car handle badly, fry wheel bearings, and who knows what else.

[Porter 21919]

They always refer to it as the backset, I measured my stock 66 rims, from mounting surface to the inside rim edge, four inches.

I checked www.americanracing.com , they had no rims for the 76 Eldo so I couldnt get a spec. I refer to their rims all the time, click on a rim and theyll give you the backspace spec.

My 90 Chevy van rims are almost identical to my 66 rims, however the backspace is 3 3/4 which prevents installation of the wheelcover, 1/4 not enough depth on the outside.

Check this source out FWIW   http://www.stocktonwheel.com/

Porter

[Rob Gerace #16100]

Backset sounds more reasonable for a measurement of 3.31 than negative offset does.  As long as people differentiate between the two measurements.  Mixing them up could give you a very different wheel than you need!  Offset is measured from the center of the wheel.  I guess if you subtracted half the wheel width from the backset, you would get the offset.  

Rob
66 SDV

[Porter 21919]

They call it the backside spacing, in this case 86-96 Cadillac RWD 15 x 7 , 4.25 basckside spacing.

http://www.americanracing.com/appguide/final.asp?section=app&detail=7755705&car=112&descript=15X7RALLYWHE

Although these rims are 5 x 5 bolt pattern they wont fit on my 66 (15 x 6 factory rims), not enough clearance for the rear skirts, I would need custom ordered 7  rims with a 5 backside spacing. Then I could use 255 60 series tires, sans whitewall.

My five rims are all cleaned up and painted, awaiting a set of 235 75 with WW.

Porter

[David #19063]

Porter,

255 60s would mess up your speedo quite a bit, too short.

255 70s would be fine, slightly taller than the 235 75s.

255 70s are fine on a 15x6...as I currently have these on my 71 Electra and had a set on my 69 LeSabre 400.  You do not need 15x7s for these.

David

[Porter 21919]

David,

I meant 255 70 series, I goofed up, doooooh.

The six inch rim is only 1/2 inch less than the recommended minimum size for the 255 70 series, seven inch would be better.

Porter

[Steve Preston #16375]

My 76 Shop manual states:

Offset(Rim Center Line to Mounting Surface)

Calais, De Ville, Brougham, Fleetwood Seventy Five, Commercial Vehicle = .29.
Eldorado = 3.31.

I was incorrect when I said it was negative. I read these sites more and now understand better. Sorry for misleading yall.

http://www.usacomp.com/Offset.htm
http://www.rsracing.com/tech-wheel.html

A little (misunderstood) knowledge can be dangerous...............