Rim backspacing to offset

[Digitalwave]

If a staggered set of rims has 4.5" and 5.5" of backspacing, how do you turn that measurement into offset?

[E30SPDFRK]

What is the width of the wheels?

[Digitalwave]

7" and 8".

[E30SPDFRK]

Backspacing is the distance from the mounting surface to the backside lip of the wheel. Offset is the amount the mounting surface is away from the center line. Is the 4.5 backspacing on the 7 or 8 inch wheel?

[xLibelle]

wtf man... an OG like yourself should know theres a forum for this kind of thing... and the question has been answered time and time again... you ok tj???


...divide rim width in half, subtract the 4.5 and 5.5 measurements from that and convert to metric.

[Erick]

1" = 25.4mm

A 7" wheel = 177.8mm so from the inner lip of the wheel to ET0 would be at 88.9mm

Now, 4.5" = 114.3mm. Removing that from the center (114.3-88.9), you're left with 25.4mm of positive offset. (Nice coincidence)

Following the same math, that 8" wheel should have an offset of +38.1mm

If that makes any sense.

So the answer is no TJ, they are not worth buying :p

[fretburnr]

offset is backspacing minus (1/2 wheel width lip to lip). Then convert from inches to mm.

Erick, keep in mind that wheel width is measured from bead to bead, so add maybe 1/2" for lip-to-lip measurement, depending on the wheel. It's best to accurately measure.

for example, if that 8" wheel (we'll call it 8.5" lip to lip) has a 5.5 backspacing,

5.5 - (0.5 * 8.5) = 5.5 - 4.25 = 1.25". 1.25" is 31.75mm.

[Erick]

well I'm considering the seller that measured them did the right measuring. But who knows how to do that nowadays.

Perhaps it was a bad call on my side. :p

Oh, and stop browsing around for other 16" wheels and drop some sort of deposit on the Ewings already :p

[fretburnr]

no biggie. for most customers, they want to know bead-width not lip-width, as they need to know what size tire to purchase.