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Nice little Backspacing Calculator
- Thread starter GAXJ4U
- Start date
Helpful when looking for wheels one is considering for purchase. Lots of companies ex: tire rack only list in offest rather than backspacing. Most of the wheels I havbe considered buying are not in front of me for performing backspacing measurements. This is where the calculator would help.
Vanimal
NAXJA Forum User
- Location
- escondido, ca
it's also pretty easy to do in your head if you know some basic metric to SAE conversions. just take half the width of the rim and add or subtract the offset. a 15x8 wheel with a -19 offset is about a 3.25 backspacing, since 19mm is almost exactly .75". a 15x8 rim with a +19 offset would be 4.75" backspacing.
That's too boring. Calculators are much cooler. They have buttons and all. Seriously though, just trying to help guys.
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Vanimal
NAXJA Forum User
- Location
- escondido, ca
wasnt intending to ball bust, just adding to the convo in case someone didnt know how backspacing and offset were related. i use plenty of calculators myself for other stuff 
deucestudios
NAXJA Forum User
- Location
- Malvern, PA / JFC
8" wheel, 12 offset = 4.97" backspacing.
FAIL.
7.5" wheel, 0 offset = 4.25" backspacing
FAIL #2
Another good reason to know the math is if your calculator is a liar, you can tell when your calculator is lying...
FAIL.
7.5" wheel, 0 offset = 4.25" backspacing
FAIL #2
Another good reason to know the math is if your calculator is a liar, you can tell when your calculator is lying...
wasnt intending to ball bust, just adding to the convo in case someone didnt know how backspacing and offset were related. i use plenty of calculators myself for other stuff
Gotcha! :gee:
Vanimal
NAXJA Forum User
- Location
- escondido, ca
hmmm guess i was wrong, opps! i have -32 backspacing instead of -19 according to the calculator.
You mean offset? The nominal width is included in the calculator.
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Doing the math that's what I came up with as well.
This one checked out too.
I don't know man the calculator seems to be dead on.
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Vanimal
NAXJA Forum User
- Location
- escondido, ca
yes. FAIL #3
lol
deucestudios
NAXJA Forum User
- Location
- Malvern, PA / JFC
Ok, you got me curious, and I see now what I missed, here's a snip from the page source:
function calc(data){var cA7C=data.pA7C;var cA7D=data.pA7D;var cA7E=(((((((cA7C)+(1)))/(2)))+(((cA7D)/(25.4)))));data.pA7E=cA7E;};
It appears they picked 1" for the overall thickness of the inner & outer wheel lip (where it says cA7C + 1), that this is automatically adding in.
Given that, it does work at what it's doing, but 1" isn't always going to be the correct difference between the advertised wheel size and the measured wheel width outside to outside. .
function calc(data){var cA7C=data.pA7C;var cA7D=data.pA7D;var cA7E=(((((((cA7C)+(1)))/(2)))+(((cA7D)/(25.4)))));data.pA7E=cA7E;};
It appears they picked 1" for the overall thickness of the inner & outer wheel lip (where it says cA7C + 1), that this is automatically adding in.
Given that, it does work at what it's doing, but 1" isn't always going to be the correct difference between the advertised wheel size and the measured wheel width outside to outside. .
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