Decipher this please...

[Brandy]

This **** just confuses me. TBI wont let me understand this crap about sizing wheels. Help please.
What I need is two wheels that are 15x10 with 5.4.50 pattern and 7 1/2" backspacing. Period. What the hell is this 'offset' crap? Does this add to the backspacing? Taken away from it? Why does every wheel have this additional measurement included making it impossible to get the wheel you need straight up? Damn it. I'm sick of looking for wheels and finding this list of confusing crap.

GHost.
JEGS SSR Spike Wheel 15 x 10 | 5 x 4.5” Wheel Bolt Pattern Spacing | +51mm Offset | 7.5” Backspacing | Gloss Black with Milled Spoke Accents | 3.27” Center Bore

 

[beanhead]

This **** just confuses me. TBI wont let me understand this crap about sizing wheels. Help please.
What I need is two wheels that are 15x10 with 5.4.50 pattern and 7 1/2" backspacing. Period. What the hell is this 'offset' crap? Does this add to the backspacing? Taken away from it? Why does every wheel have this additional measurement included making it impossible to get the wheel you need straight up? Damn it. I'm sick of looking for wheels and finding this list of confusing crap.

GHost.
JEGS SSR Spike Wheel 15 x 10 | 5 x 4.5” Wheel Bolt Pattern Spacing | +51mm Offset | 7.5” Backspacing | Gloss Black with Milled Spoke Accents | 3.27” Center Bore

It's just a different way of measuring the same thing, really..
Offset is the distance, in millimeters, that the mounting surface is moved off of centered, with positive offset being closer to the wheel face, and negative offset being closer to the inside....whereas Backspacing is measured from the mounting surface, to the overall inside edge of the wheel (the part that's gonna hit the leaf spring or fender well first).
What makes it more confusing is that advertised wheel widths are NOT the overall width....so an 8" advertised wheel has an actual overall width of 9", and that's what you need to know when calculating backspacing.

So your +51mm offset means the mounting surface of the wheel is 51mm toward the outside of the wheel as measured from dead center of the wheel. If the mounting surface was on dead center, that would be zero offset.

If you know that the backspacing and wheel size you want are correct, you can ignore the offset...

It's obviously a system devised by some foreigner to try to confuse us into going metric

 

[Brandy]

It's just a different way of measuring the same thing, really..
Offset is the distance, in millimeters, that the mounting surface is moved off of centered, with positive offset being closer to the wheel face, and negative offset being closer to the inside....whereas Backspacing is measured from the mounting surface, to the overall inside edge of the wheel (the part that's gonna hit the leaf spring or fender well first).
What makes it more confusing is that advertised wheel widths are NOT the overall width....so an 8" advertised wheel has an actual overall width of 9", and that's what you need to know when calculating backspacing.

So your +51mm offset means the mounting surface of the wheel is 51mm toward the outside of the wheel as measured from dead center of the wheel. If the mounting surface was on dead center, that would be zero offset.

If you know that the backspacing and wheel size you want are correct, you can ignore the offset...

It's obviously a system devised by some foreigner to try to confuse us into going metric

So, just to clarify....lol.....since this particular wheel is the correct size, the correct back space of 7.50 I then can ignore the MM offset number? It doesn't add to the backspacing. What I get from that is that the placement of the mounting surface is moved from dead center to 51mm towards the face of the wheel. and THEN the back space is measured from THAT surface position. Making the offset irrelevant except to a handful of Brainiac's who want the thing to look a certain way.
Yes?
What about the center cap hole diameter of 3.27"? Is that what B Bodies are? If not, then what are they?

 

[beanhead]

So, just to clarify....lol.....since this particular wheel is the correct size, the correct back space of 7.50 I then can ignore the MM offset number? It doesn't add to the backspacing. What I get from that is that the placement of the mounting surface is moved from dead center to 51mm towards the face of the wheel. and THEN the back space is measured from THAT surface position. Making the offset irrelevant except to a handful of Brainiac's who want the thing to look a certain way.
Yes?
What about the center cap hole diameter of 3.27"? Is that what B Bodies are? If not, then what are they?

Yeah, just ignore it. All it's telling you is where the mounting surface is located, in relation to dead center of the wheel...which doesn't really matter in this case. Backspacing is more relevant, that's how far the inside edge of the rim is going to actually be from the mounting surface.

And I don't remember our center hub size...but most modern aftermarket wheels are "lug-centric" and the center hole is oversized to fit a variety of car makes.
You might want to look that up just to make double sure you don't get a wheel with a hole smaller than the hub...but I think Mopars were 2-something inches so you should be good.

Some guys say lug-centric isn't good, they need to be snug around the center, blah blah blah but that's BS pretty much all wheels are lug-centric anymore and nobody's wheels are falling off or causing any problems. My Torq-Thrusts are lug-centric and center on the hub just fine.

 

[Dave6T4]

51 mm. is 2", if that helps.

 

[R/T Boy 67]

B bodies have roughly 2.8" diameter hubs.

 

[HEMI-ITIS]

Backspacing is measured by laying a straight edge on the back of the rim,then measure from the bottom of the straight edge to the mounting surface.

 

[Brandy]

Here's the wheel, one piece aluminum.