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Clinton
31st March 2009, 10:11 PM
alot of guys are kind of confused about the whole offset thing with positive and negative offset. hopefully this can help guys out from now on

http://www.tirerack.com/images/wheels/tech/offset.gif

The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types.

ZERO OFFSET

The hub mounting surface is even with the centerline of the wheel.

POSITIVE OFFSET

The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars.

NEGATIVE OFFSET

The hub mounting surface is toward the back or brake side of the wheels centerline. "Deep dish" wheels are typically a negative offset.


MEASURING OFFSET

To determine the offset, the wheel must be measured accurately using the following steps:



1) measure the overall rim width of the wheel.
2) measure the backspace, which is the measurement from the hub surface contact area to the outside of the inner rim.
3) divide the overall rim width by 2 which gives you the center line.
4) subtract the center line (overall rim width divided by 2) from the backspace.
5) a negative answer means the wheel has a negative offset and a positive answer means the wheel has a positive offset

gumbie
31st March 2009, 10:36 PM
This should help millions, gw champ :).

Oversized 86
31st March 2009, 11:13 PM
http://www.1010tires.com/WheelOffsetCalculator.asp

add that to the top post also...

slide86
1st April 2009, 10:38 AM
also remember, dont measure from the outside of the lip to lip

its from the bead sealing edge to edge. people get caught out on that too

redsprinter
1st April 2009, 11:10 AM
a couple of dumb question with i think easy answers .

1. how do ppl know by just looking at the wheels in a picture what offset the wheel are ?

2. how do you know what offset you need for you car >? all good to know how to work out the offset the wheel has .. but how do i apply it to actual fitting them on or getting it flushed with the guard without scraping anything in the inner gurads .

slide86
1st April 2009, 11:51 AM
buy the wheels then get the car to fit around them....maximum win

adam
1st April 2009, 04:13 PM
also remember, dont measure from the outside of the lip to lip

its from the bead sealing edge to edge. people get caught out on that too

Measuring from lip to lip will work fine when trying to find offsets. It's when you're trying to determine the wheel width that you should measure from where tyre would bead.

adam
1st April 2009, 04:15 PM
a couple of dumb question with i think easy answers .

1. how do ppl know by just looking at the wheels in a picture what offset the wheel are ?


Some wheels come in certain widths and offsets. You can usually tell which ones they are comparing to guard clearance. It's when you have camber it gets a little tricky. Camber does a lot!

Chairs with flares
1st April 2009, 05:50 PM
buy the wheels then get the car to fit around them....maximum win


+1

:thumbup:

4.5AG
1st April 2009, 09:47 PM
Try this website..Very handy

http://www.1010tires.com/WheelOffsetCalculator.asp

Mr Fujiwara
1st April 2009, 10:03 PM
yeh buy and try its the best way :)

djscheppy
2nd April 2009, 05:02 PM
i was trying to find information on this.
was trolling the forums for a while and putting pieces of info together.
this would have saved a few hrs of my life :(

banzai_pots
2nd April 2009, 09:53 PM
mitve been covered but, is offset measured in mm?

Konakid
2nd April 2009, 10:05 PM
Correct

Chairs with flares
3rd April 2009, 03:21 AM
X-posted from the technical questions forum since it's relavent...



To throw a spanner in the works, clearance has to be calculated with wheel width and tire section width in consideration.

i.e. a 15x7J +15 wheel will sit out further than a 15x6 +15 wheel. It will sit 13mm/half inch further out because of the extra width (half inch wider strut side and half inch street side).

HOWEVER; the edge of the tire (assuming no stretch) will sit exactly the same on either wheel, it will just apear to have less bulge on the 15x7J wheel.

In my experience, I found ran 205/50 R15 tires non stretched. With the same tires, I went from a 15x7J +24 wheel to a 15x6J +13 wheel. The outer lip of the wheel sat pretty much the same with the new wheel as the extra offset was cancelled out by the wheel being narrower. But the tire tread sat out an extra 11mm since where the tire tread sits can be deduced from offset alone (assuming no stretch).

Cliff notes:
- Offset numbers will dictate where your tire tread will sit.
- Where your wheel edge will sit will need to take wheel width into consideration.

driftke70
3rd April 2009, 07:30 PM
for this reason, it is sometimes possible to get a higher profile stretch under a guard than a lower, also, brings more significance into your ride height. But if you talking differences between 6 and 7 your missing the point.

Nic19
4th April 2009, 03:03 PM
how can i tell what offset i will get if i reverse my meshies? they are 15x7 +25

Chairs with flares
4th April 2009, 03:59 PM
how can i tell what offset i will get if i reverse my meshies? they are 15x7 +25


My guess from rough calculations would give you around a -50 offset.

This is assuming the wheel is 3pc and the where the center bolts up to the barrel/lip is the same 'offset' as the hub mounting face.

I could be wrong... very wrong...

Konakid
4th April 2009, 08:52 PM
how can i tell what offset i will get if i reverse my meshies? they are 15x7 +25

Reverse them then use them as anal plugs in the Mardi Gra.

Chairs with flares
4th April 2009, 09:35 PM
But if you talking differences between 6 and 7 your missing the point

Just an example; same principles apply to calculations or comparisons between an 8J and 9J wheel.




Reverse them then use them as anal plugs in the Mardi Gra.

Meshies?
As a plug?
FAIL!

You'd clearly need SSR Mk1's or something similar with a flat face and no spokes...

:cries: