Wheel offsets for Dummies ??? Help Please??

[B-Man]

Hi,

Can someone please explain to me in very simple to undersand terms, what the fark wheel offsets are and how to choose the right ones ??

For example: I have 17" x 8" wheels on the front and 17" x 9" wheels on the back of my R33 GTS-t.

The dish size is different front to rears, as expected - is this just the diff in width or does offset have something to do with it ??

What is the ideal offset (without having to use spacers) for 17" x 8" (fronts) and 17" x 9" (rears)

Are these the best size (width) ?? or should I look at going wider by 0.5" per wheel ?? If so , does this change the offset???

Please Explain ???

Cheers,

[B-Man]

Bump..

[Duncan]

Brendan...calculator here:

http://toy4two.home.mindspring.com/offset.html

And once you've worked out the answer, how about posting it in the FAQ section, coz this gets asked a lot....

[B-Man]

Yeah - asked a lot - but no answers - try a seach.......

I looked at the calculator thingy but no help as it assume you know WTF you are talking about .....

[Duncan]

well, from meggala's site (great info! http://www.meggala.com/wheelsoffsets.htm) stock wheel sizes and offset for r33 gtst is:

F: 16 X 7.0 +33

R: 16 X 8.0 +38

the problem is I've got no idea of the clearance inside and out for the stock wheels so I can't use the calc either Anyone got those measurements?

[B-Man]

Got the info:

32 to 35 front and 38 to 40 rears

[PranK]

Hey B-Man, did it explain to you what the offset is? did you still want to know?

[B-Man]

No it didn't - and Yes I do - please tell ! !

[blind_elk]

offset is:

backspace - (width / 2)

backspace is the distance from the rim to the surface that mounts against the hub.

[Jimbo2000]

does that mean..

backspace minus (width divided by two)?

[B-Man]

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.

If the offset of the wheel is not correct for the car, the handling can be adversely affected. When the width of the wheel changes, the offset also changes numerically. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most cars, this won't work correctly. We have test fitted thousands of different vehicles for proper fitment. Our extensive database allows our sales staff to offer you the perfect fit for your vehicle.

[XEQTOR]

Interesting info guys!!!! Wish i had seen this prior to buying my 18 x 8 and 18 x 9's, dont know there offsets but they look fooorking fantastic!!!!

[PranK]

nice find B-Man!!!

[benm]

So basically their is no "set" offset for each car it just depends on:

* How you want it to look

* How the car will handle

ie; the difference between an offset of 35 and 38 is 3mm which will effect either looks or handling/supports.?

[red17]

Err yes there is a "Set" offset for each car, especially when your talking about a skyline. 4 pot brakes make it mighty difficult to bolt on just any rim with any offset.

My 32 has +35's all round... the difference between a 35 and a 38 is minimal in terms of looks, and id doubt itd make a major handling difference.

Bear in mind not all rims come in all offsets, which means its quite common for people to buy a set of second hand rims without thinking about it only to find it doesnt clear the brakes or sticks out the guards by a good few cm.

Red17

[Downforce]

Guys, if you want a better understanding of wheel offset and backspace, read this page - http://www.usacomp.com/Offset.htm

It's probably the most useful page I've seen which best describes wheel offsets. I know this has always been a confusing concept for many people, but once you understand it's really quite simple.

Cheers.

[SKY031]

http://www.usacomp.com/Offset.htm

[lwells]

Wheel offset will also affect your track width I believe. That's rather important in some states as you are only allowed a certain increase/decrease in width.

Or am I just wrong and muddying the waters?

Lucien.

[Duncan]

Absolutely. Offset can change the wheel track, more (posative) offset = more track width.

but of course you still need to clear the brakes and suspension on the inside, and be careful of moving the wheel out beyond the standard guards, also illegal

[INASNT]

On my new 18's i got +38 offset front and back, but the front brakes just clear the rims, like 1-2 mm, so i would go +35 offset for the fronts B-man. I had no choice as they didnt have +35 offset for my rims.

You see alot of skylines going around with the wrong offsets that makes the rims sit inside the guards coz some tyre places dont know shit and will just supply fwd +45 offsets for skylines, which looks shit.