Need some input on these wheels backspacing/offset

[dbals]

Ok guys Im looking at the Ultra Predetor wheel. It comes in these size combos
18X9 5 1/2 backspacing +14 offset
or
18x9 6 1/8 backspacing +32 offset

I want the wheel that will fit the best under the truck with out sticking out. Can someone explain the math to me on the backspacing/offsett so I can figure that out I want to make sure I fully understand how to figure where these wheels will be compared to the factory 17s....or is there a good wheel calculator out there that will do this math for us??
thx all
-Drew

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04 Quad Cab 4x4....Bone Stock Baby

[dbals]

and if someone could also comfirm stock wheel size/backspacing/offset that would be great. I believe it is a 17x9 with 6.25 of backspacing 0 offset but not 100% positive.
thx

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04 Quad Cab 4x4....Bone Stock Baby

[dbals]

come on guys need a little help....if someone could just explain how to do the math on this I would appreciate it.
thx

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04 Quad Cab 4x4....Bone Stock Baby

[Big Nasty]

backspace is the distance between inner lip of the wheel and the mounting pad. Offset is the measurement (usually in mm) from the centerline of the wheel and the mounting pad. The higher the offset the close the mounting pad will be to the outer lip of the wheel where as a low offset the mounting pad will be close to the hub. Your Second choice (18x9 6 1/8 backspacing +32 offset) are close to the stock numbers therefore the tires will be under the fenders. The first choice (18X9 5 1/2 backspacing +14 offset) will stick out about an inch further than the stock wheels.

Here's a couple of quick links to take a look at.

Wheel Tech - Offset

Wheel Offset Calculator

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'03 3500 QC SB 6sp 4x4 / MBRP 4" Turbo Back / Diablosport Predator/Puck / AEM Workhorse / ISSPro Gauges / 18" American Racing Cannon Wheels / 325/60/18 Terra Grapplers

[dbals]

Originally Posted by Big Nasty

backspace is the distance between inner lip of the wheel and the mounting pad. Offset is the measurement (usually in mm) from the centerline of the wheel and the mounting pad. The higher the offset the close the mounting pad will be to the outer lip of the wheel where as a low offset the mounting pad will be close to the hub. Your Second choice (18x9 6 1/8 backspacing +32 offset) are close to the stock numbers therefore the tires will be under the fenders. The first choice (18X9 5 1/2 backspacing +14 offset) will stick out about an inch further than the stock wheels.

Here's a couple of quick links to take a look at.

Wheel Tech - Offset

Wheel Offset Calculator

Thanks Big Nasty, I appriciate it. Can you possible confim the stock wheel settings for me....ive heard that the stock wheel backspacing is 6.25 and offset is 0 but ive dont the math on this and a 0 offset just doenst seem right??

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04 Quad Cab 4x4....Bone Stock Baby

[silverdog]

I believe the stock wheels have 6.25" of backspacing and are 8" wide.

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07 SLT, Quad, 48RE, Westin bars, 2" Leveling kit., SMARTY!, DiProcal pyro, boost, trans gauges: looking at tires and wheels

[Big Nasty]

Originally Posted by silverdog

I believe the stock wheels have 6.25" of backspacing and are 8" wide.

that sounds about right - that would put the offset at about a +44

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'03 3500 QC SB 6sp 4x4 / MBRP 4" Turbo Back / Diablosport Predator/Puck / AEM Workhorse / ISSPro Gauges / 18" American Racing Cannon Wheels / 325/60/18 Terra Grapplers

[Eric]

Stock - 17X8, +43.1 mm offset, 6.25" backspacing.

Your second wheel option will be closer to stock than the first.