Wheel Backspacing for Cromodora Daytona CD31 wheels

joelman919

Low Mileage
Please help

I have Cromodora Daytona CD31 wheels 5 1/2 x 13, 4x98 wheels (set of four)

I need to know (without having access to my car right now) what is the "wheel backspace" on this set of wheels?

I have been looking around on the internet and on the XWeb and I have not been able to find this bit of information.

Anyone know what the wheel backspacing is for these wheels?
 
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Cromodora CD 31

Cromodora CD 31 - specifications

Rim material: Magnesium
Rim width x diameter (inches): 5,5Jx13
Offset: 18
Bolt pattern: 4x98
Weight: 4,35 kg
Year:
Manufacturer part number:
Cars: Fiat 124 Coupe / Spider / Berlina, Fiat 125, Fiat 132, Fiat 128 Coupe / Rallye, Fiat X1/9, Fiat 131 Berlina / Familiare, Alfa Sud
 
Rachel, Joel... I'm not understanding the math here...

5.5 inches = 139.7mm which would be the overall width of the wheel not including the "lip"... but this would be close enough for this discussion.

The center of the wheel, or ZERO offset would be 2.75 inches or 69.85mm.

With an 18mm "positive" offset, would we not add the 18 mm to 69.85 mm which would then equal 87.85 mm or about 3.45 inches?

100.55 mm = 3.95 inches and leaving only about 1.55 inches of material left.

The foto below is a 14 x 6 with a 22 mm offset...



... and it indeed shows that possibility of Chromodora building wheels with 3.86 inches total positive offset... and leaving only 2.14 inches of material in the front of it.

Basically, what I am saying is that what Rachel stated can be true... but does not appear to match the math for the 18 mm offset (87.85) for this wheel.

Did I miss something?
 
The nominal width of the wheel is taken between the tyre bead contact faces, this is your 5.5". The backspace is measured from the mounting hub face to the inner edge of the wheel, i.e. the "lip". The lip is generally around half an inch wide. Therefore the actual overall width of the wheel is 5.5 + 1 = 6.5".

The offset is measured from the centreline of the wheel to the hub face, +18 mm offset means the hub face is 18 mm towards the outside of the wheel from the centreline. The centreline is 6.5"/2 x 25.4 mm = 82.55 mm from the inner edge of the wheel. Adding this the 18 mm offset gives you the 100.55 mm.

Your 14x6 wheel's backspace is thus (6+1)/2 x 25.4 + 22 = 110.9 mm.
 
Indeed... I guess where I went wrong was thinking...

the extra 1/2 of the lip was insignificant... but I see and actually agreed all along that it is NOT! I just got off on the wrong foot and kept on going. HA!

Thanks...

BTW... did it ever cross your mind with the trend towards using the METRIC system worldwide... (as most already do...) Why is it that we still measure Rim Diameters and Cross Sections in INCHES... and why do we use METRIC figures for overall tire sizes... and then still use INCHES for the diameter?
 
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