Can ya'll help me figure out the math?

[OFC Ranger]

Current setup is 285/70/17 on factory 17" sport wheels with a 2" wheel spacer.

I want to start shopping for after market wheels in the future. I would like an after-market wheel that might eliminate the spacer, but keep me at my current stance. I am also looking for a simple design that is easy to clean in black or a gunmetal dark gray.

So did I read correctly that factory sport wheels are 42 offset? And 2" spacer would equate to 50 offset? I need some math wizards to spit out what offset Im looking for to keep tires wider like they are now.

I am really digging the Fuel Vector, just now sure if they sell in an offset Im looking for?

Also kinda digging the cheaper Pro-Comps....

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[cfhgarza]

Isn't a spacer going to decrease the offset? Pretty sure the factory offset is 55mm. You would have to convert the 2" to mm then subtract.

 

[OFC Ranger]

I believe I recall reading that every 1" is 20mm (rounded)?

 

[Ranger Roger]

I believe I recall reading that every 1" is 20mm (rounded)?

25.4 mm/inch

 

[OFC Ranger]

Ah ok, so factory wheel + 2" wheel spacer equals 4+ offset (rounded)?

That seems sort of odd cause this setup put about 1" (maybe a little more) rubber outside the stock fenders. Hrmmm

 

[ParkerAzJeff]

The Sport wheels have a +55mm offset. 2 inch spacers move it out 25 mm per inch essentially changing the offset to +5 offset. I'm running Icon Rebound wheels that are +25mm and have no issues rubbing but my tires are 265/70R17

 

[OFC Ranger]

Not worried about rubbing thankfully, I did a full crash bar delete until I order some aftermarket ones. I thought negative offset pushes the tire out and positive tucks it in further? Im still new to this kind of stuff and Im like whaaaaa...?

I'm running Icon Rebound

Dang I kind of like those too.

 

[ParkerAzJeff]

Ah ok, so factory wheel + 2" wheel spacer equals 4+ offset (rounded)?

That seems sort of odd cause this setup put about 1" (maybe a little more) rubber outside the stock fenders. Hrmmm

Zero offset means the mounting face & center of the tire are dead on in the middle. Negative offset moves the tire farther out from the center line. Positive offset moves the center line of the tire towards the middle of the vehicle.

 

[cfhgarza]

I thought negative offset pushes the tire out and positive tucks it in further?

Anytime you take away offset it's going to push it out. 0 offset is dead center.

You're pretty close to being 0 offset with those spacers since 2" is equal to 50.8mm

 

[cfhgarza]

A

 

[gfitzge2]

This may help you.

Offset & Backspace - How Do They Relate?

​

Offset and backspace are essentially two different ways of looking at the same thing. They determine the location of the wheel and tireassembly when bolted to the vehicles hub.

Offset is the measured distance between the hub mounting surface and the wheels center line.

With X being the determined offset, the hub mounting surface on positive offset wheels is X amount forward from the wheel center line. The hub mounting surface on negative offset wheels is X amount backwards from the wheel center line. The hub mounting surface on 0 offset wheels is the wheel center line.


Backspacing is the measurement from the hub mounting surface to the back edge of the wheel.

***Typically speaking, the higher the offset/backspace, the more the wheel will tuck inwards towards the suspension or away from the fender. The lower the offset/backspace, the more the wheel will push out away from the suspension or towards the fender.

For Example:

*If the offset on a 9" wide wheel is +12mm, the hub mounting surface will be 12mm forward from the wheels center line. Measuring from the hub mounting surface to the back edge of the wheel, the backspacing is 5.5"

*If the offset on a 9" wide wheel is -12mm, the hub mounting surface would be 12mm towards the back of the wheel from the wheels center line. Measuring from the hub mounting surface to the back edge of the wheel, the backspacing is 4.5"

Here's how to calculate the backspacing using the rim width and offset:
First - add 1" to the rim width and then divide by 2 to find the wheels center line (you have to account for the wheel flange which is why you add 1" to the rim width) . Second - convert the offset which is in millimeters into inches. There is 25.4mm in 1 inch so divide the offset by 25.4. Lastly - add the converted offset to the wheels center line if the offset is positive for the correct backspacing. Subtract the converted offset to the wheels center line if the offset is negative for the correct backspacing.

For Example:

17x9 +12mm offset
*9" rim width + 1" = 10"
*10"/2 = 5" (wheels center line)
*+12mm offset/25.4 = 0.47" (0.50" rounded up)
*0.50" + 5" = 5.50" Backspace

17x9 -12mm offset
*9" rim width + 1" = 10"
*10"/2 = 5" (wheels center line)
*-12mm offset/25.4 = 0.47" (0.50" rounded up)
*0.50" - 5" = 4.50" Backspace

***Please note that the wheels center line is the backspacing for 0 offset wheels.

 

[Jms81661]

This may help you.

Offset & Backspace - How Do They Relate?

​

Offset and backspace are essentially two different ways of looking at the same thing. They determine the location of the wheel and tireassembly when bolted to the vehicles hub.

Offset is the measured distance between the hub mounting surface and the wheels center line.

With X being the determined offset, the hub mounting surface on positive offset wheels is X amount forward from the wheel center line. The hub mounting surface on negative offset wheels is X amount backwards from the wheel center line. The hub mounting surface on 0 offset wheels is the wheel center line.


Backspacing is the measurement from the hub mounting surface to the back edge of the wheel.

***Typically speaking, the higher the offset/backspace, the more the wheel will tuck inwards towards the suspension or away from the fender. The lower the offset/backspace, the more the wheel will push out away from the suspension or towards the fender.

For Example:

*If the offset on a 9" wide wheel is +12mm, the hub mounting surface will be 12mm forward from the wheels center line. Measuring from the hub mounting surface to the back edge of the wheel, the backspacing is 5.5"

*If the offset on a 9" wide wheel is -12mm, the hub mounting surface would be 12mm towards the back of the wheel from the wheels center line. Measuring from the hub mounting surface to the back edge of the wheel, the backspacing is 4.5"

Here's how to calculate the backspacing using the rim width and offset:
First - add 1" to the rim width and then divide by 2 to find the wheels center line (you have to account for the wheel flange which is why you add 1" to the rim width) . Second - convert the offset which is in millimeters into inches. There is 25.4mm in 1 inch so divide the offset by 25.4. Lastly - add the converted offset to the wheels center line if the offset is positive for the correct backspacing. Subtract the converted offset to the wheels center line if the offset is negative for the correct backspacing.

For Example:

17x9 +12mm offset
*9" rim width + 1" = 10"
*10"/2 = 5" (wheels center line)
*+12mm offset/25.4 = 0.47" (0.50" rounded up)
*0.50" + 5" = 5.50" Backspace

17x9 -12mm offset
*9" rim width + 1" = 10"
*10"/2 = 5" (wheels center line)
*-12mm offset/25.4 = 0.47" (0.50" rounded up)
*0.50" - 5" = 4.50" Backspace

***Please note that the wheels center line is the backspacing for 0 offset wheels.

This just makes it more confusing. Made my head hurt reading it....3x.lol

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