Could someone do the OS math
#1
07-13-2016, 02:01 PM
#3
07-13-2016, 02:41 PM
#4
07-13-2016, 07:34 PM
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#6
07-14-2016, 10:28 AM
Veteran Member
#7
07-14-2016, 10:34 AM
Custom wheel Primer
So if I wanted to get a set of wheels custom made and widen the stance by 15mm to eliminate the adapters, I would subtract 15mm from the oem offsets giving me:
OEM Fronts 20x9.0" @ 55mm (-15mm) = 40mm
OEM Rears 20x10.5" @ 38mm (-15mm) = 23mm
These should be the correct offsets for oem wheel widths if I want to widen my stance 15mm.
Now say I want my new wheel sizes to be 10" and 11.5" instead of 9.0" and 10.5" so I need to figure out my new offsets with rims 1" wider both front and rear.
Custom Fronts 20x10.0" @ 53mm offset
Custom Rears 20x11.5" @ 36mm offset
OEM Fronts 20x9.0" @ 55mm (-15mm) = 40mm
OEM Rears 20x10.5" @ 38mm (-15mm) = 23mm
These should be the correct offsets for oem wheel widths if I want to widen my stance 15mm.
Now say I want my new wheel sizes to be 10" and 11.5" instead of 9.0" and 10.5" so I need to figure out my new offsets with rims 1" wider both front and rear.
Custom Fronts 20x10.0" @ 53mm offset
Custom Rears 20x11.5" @ 36mm offset
Last edited by polarisnavyxj; 07-14-2016 at 03:04 PM.
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#8
07-14-2016, 10:51 AM
Veteran Member
So if I wanted to get a set of wheels custom made and widen the stance by 15mm to eliminate the adapters, I would subtract 15mm from the oem offsets giving me:
OEM Fronts 20x9.0 @ 55mm (-15mm) = 40mm
OEM Rears 20x10.5 @ 38mm (-15mm) = 23mm
Now to widen the rim widths:
Because 12mm = .5", I would subtract half this amount or 6mm (dividing the difference inside and outside the mount flange, in order the get my accurate offsets for wheels that are wider than oem.
For example, if my rear wheel was 11" instead of 10.5", My offset would move from 23mm to 17mm.
Another way to go about this out would be to widen the wheels instead of changing the offsets.
If our target is to widen our stance 15mm by widening our wheels, we could do 10.5" in the front. This would add .75" (1/2 of (10.5"-9.0")) or 19mm to our stance. We can then back off 4mm, or 44mm to get the offset correct in the front.
In the rear, using the same math, we can do the same thing and move to a 12" (+1.5") rim width and back off he same 4mm leaving us with 27mm as the correct offset.
Custom Fronts 20x10.5" = 44mm offset
Custom Rears 20x12.0" = 27mm offset
This should give us wider rims, plus the 15mm spread.
Is this correct?
OEM Fronts 20x9.0 @ 55mm (-15mm) = 40mm
OEM Rears 20x10.5 @ 38mm (-15mm) = 23mm
Now to widen the rim widths:
Because 12mm = .5", I would subtract half this amount or 6mm (dividing the difference inside and outside the mount flange, in order the get my accurate offsets for wheels that are wider than oem.
For example, if my rear wheel was 11" instead of 10.5", My offset would move from 23mm to 17mm.
Another way to go about this out would be to widen the wheels instead of changing the offsets.
If our target is to widen our stance 15mm by widening our wheels, we could do 10.5" in the front. This would add .75" (1/2 of (10.5"-9.0")) or 19mm to our stance. We can then back off 4mm, or 44mm to get the offset correct in the front.
In the rear, using the same math, we can do the same thing and move to a 12" (+1.5") rim width and back off he same 4mm leaving us with 27mm as the correct offset.
Custom Fronts 20x10.5" = 44mm offset
Custom Rears 20x12.0" = 27mm offset
This should give us wider rims, plus the 15mm spread.
Is this correct?
#9
07-14-2016, 12:16 PM
Your question/assumptions do not include tire size (most importantly width) which is also a factor in the equation. Use the Wheel Calculator in the Tools tab at the top of this webpage so you can look at all of the possible permutations. Keep in mind, matched tires (front/rear) do not come in all sizes. You also need to calculate the tire diameter (or sidewall) to ensure that you don't stray too far from the OEM spec.
Does the wheel math look right?
#10
07-14-2016, 12:50 PM
#11
07-14-2016, 12:59 PM
also like ungined said ....tire size is important. unless you want a streched tire, on that 12" wide rear, you would need to step up to a 315 or 325 section rear. that added width needs to be accounted for as well.
as you increase offset in combination with the wider tire, you need to account for clearance on the inside of the wheel well.
with a 12" rear wheel your offset should be somewhere in the 42-43 range.
edit. corrected to fix my math.
as you increase offset in combination with the wider tire, you need to account for clearance on the inside of the wheel well.
with a 12" rear wheel your offset should be somewhere in the 42-43 range.
edit. corrected to fix my math.
Last edited by ShaunPA; 07-14-2016 at 01:06 PM.
#15
07-14-2016, 02:50 PM
I saw the tire sizes and thought this was a calculator to compare tire sizes but I see now how to do wheel offsets.
Data fixed above!
OK - with the 1" wider wheel sizes, now the calculator shows:
Front: 25.7mm less inner clearance.
Rear: 25.7mm less inner clearance.
We have extended the stance out 15mm on each side how can it be we lose this much inner clearance when we only increased the wheel size an effective 13mm (1/2")?
What am I doing wrong?
Last edited by polarisnavyxj; 07-14-2016 at 03:13 PM.
#16
08-05-2016, 04:21 PM
I found these wheels that are available in 9, 10.5, and 11.5
Ferrada Wheels FR2 20x 9.0 5x108 et35 Matte Black
Ferrada Wheels FR2 20x10.5 5x108 et38 Matte Black
Ferrada Wheels FR2 20x11.5 5x108 et30 Matte Black
Don't forget I want the wheels to be as wide as oem with adapters or a +15mm
One more time, just to be sure, could I go with the wider stagger without adapters? The calculator seems to adjust for tire sizes.
Ferrada Wheels FR2 20x10.5 5x108 et38 Matte Black
Ferrada Wheels FR2 20x11.5 5x108 et30 Matte Black
Don't forget I want the wheels to be as wide as oem with adapters or a +15mm
One more time, just to be sure, could I go with the wider stagger without adapters? The calculator seems to adjust for tire sizes.
Last edited by polarisnavyxj; 08-05-2016 at 04:24 PM.
#17
08-06-2016, 06:03 AM
Veteran Member
#18
08-06-2016, 07:39 AM
Veteran Member
Ferrada Wheels FR2 20x 9.0 5x108 et35 Matte Black
Ferrada Wheels FR2 20x10.5 5x108 et38 Matte Black
Ferrada Wheels FR2 20x11.5 5x108 et30 Matte Black
Don't forget I want the wheels to be as wide as oem with adapters or a +15mm
One more time, just to be sure, could I go with the wider stagger without adapters? The calculator seems to adjust for tire sizes.
Ferrada Wheels FR2 20x10.5 5x108 et38 Matte Black
Ferrada Wheels FR2 20x11.5 5x108 et30 Matte Black
Don't forget I want the wheels to be as wide as oem with adapters or a +15mm
One more time, just to be sure, could I go with the wider stagger without adapters? The calculator seems to adjust for tire sizes.
2. The 20x10.5 rear is the same offset as stock and will therefore need a 15 or 17mm spacer to match the front extension of the new front wheel.
3. The 20x11.5 may push the the face out beyond the fender well (+20mm). If you don't lower the car, that might be ok.
#19
08-06-2016, 12:57 PM
1. The 20x9 front wheels will push the face out by by 17mm without a spacer, which will look good. (I'm using a 17 mm spacer with the OEM wheel)
2. The 20x10.5 rear is the same offset as stock and will therefore need a 15 or 17mm spacer to match the front extension of the new front wheel.
3. The 20x11.5 may push the the face out beyond the fender well (+20mm). If you don't lower the car, that might be ok.
2. The 20x10.5 rear is the same offset as stock and will therefore need a 15 or 17mm spacer to match the front extension of the new front wheel.
3. The 20x11.5 may push the the face out beyond the fender well (+20mm). If you don't lower the car, that might be ok.
So the 9 + 11.5 might be the ticket to lose the spacers - huh? For the rear what would be your tire recommendation with the 11.5" spread but not to go any wider?
Oh and by the way, I think the 10.5" is meant for the front, not the rear - for a 10.5 F + 11.5 R staggered fitment. Would that make more sense? The staggered sets come 9 + 10.5, and 10.5 + 11.5 in the packages on the site which may explain why the 10.5 would need adapters on the rear.
Last edited by polarisnavyxj; 08-06-2016 at 01:08 PM.
#20
08-06-2016, 03:52 PM
Veteran Member
So the 9 + 11.5 might be the ticket to lose the spacers - huh? For the rear what would be your tire recommendation with the 11.5" spread but not to go any wider?
Oh and by the way, I think the 10.5" is meant for the front, not the rear - for a 10.5 F + 11.5 R staggered fitment. Would that make more sense? The staggered sets come 9 + 10.5, and 10.5 + 11.5 in the packages on the site which may explain why the 10.5 would need adapters on the rear.
Oh and by the way, I think the 10.5" is meant for the front, not the rear - for a 10.5 F + 11.5 R staggered fitment. Would that make more sense? The staggered sets come 9 + 10.5, and 10.5 + 11.5 in the packages on the site which may explain why the 10.5 would need adapters on the rear.
2. You can't use the 10.5" on the front at all since it pushes the face more than 33mm outward. Close to an inch of tire would not be covered by the fender.