wheel offset question

[kwayne]

stock offset = 55mm; if I put on a bolt pattern adapter (to change from 5-110 to 5-114.3(4.5")), that is 25.4mm(1") thick- what offset on the wheels should i get.

changing the bolt pattern gives alot more wheel choices.

[lil goat]

There is 25.4 MM in an inch. so an 80 mm offset would be the same as stock. You should be able to figure it out from there, you could most likely still use stock but I think that might be as low as you could go. Not sure I would like it on the front?

[My-Low-Sol]

Are there more wheel choices in 5-114 bolt pattern? Yes.

Do any of them have the required offset to work with a 1" spacer? No.

An 8" wide wheel with a 80mm offset does not exist AFAIK. On the stock wheels the hub mounting surface is already pretty darn close to the face of the wheel. An 80mm offset wheel would have the hub mounting surface about 3/4" from the outer lip of the wheel. I don't think it is possible to construct a wheel with those specs.

Read more about offset here.

[kwayne]

I was under the impression that with the 1" space/adapter you would use less than stock offset; 55.0-25.4=29.6 to remain stock.

[USC_Solstice]

No they are correct it would be an 80mm offset to have the wheel center in the correct position. And the spoke design is what would determine whether that offset is possible or not. Its not a typical offset but its definitely possible.

[John Richards]

I'm pretty sure that My-Low-Sol is correct that the 80mm offset would be needed to compensate for the 1" spacer. However, I have 38mm offset wheels and they stick out only 1/8" beyond the wheel wells, so there might be a wheel with as small as a 65mm offset that would work with a 1" spacer, although there are issues of disc brake clearance also. I would think that a wheel with between 65 and 80mm offset used with a 1" spacer should be tested for clearance (both for brakes and wheel wells), as with all wheels. The offset is what brings the wheel back in towards the center of the car because the axle mounting face is further out than the center of the wheel. My brain hurts.

[kwayne]

just found this on another forum after a google search...
"Spacers can be used to change the offset of a wheel. By bolting between the wheel and the wheel hub, they push the wheel further "out" from the car. Spacers SUBTRACT offset from a wheel setup. Therefore if you want to run an et 55 offset wheel (popular OEM Porsche application), you will need either a 15 or 20 mm spacer to end up with an offset in the acceptable range (et40 or et 35)."

and:
"A 1" thick spacer would turn a common +40 wheel into a +15 wheel."
this seems to support my theory, which is why I'm confused.

[My-Low-Sol]

Originally Posted by kwayne just found this on another forum after a google search... "Spacers can be used to change the offset of a wheel. By bolting between the wheel and the wheel hub, they push the wheel further "out" from the car. Spacers SUBTRACT offset from a wheel setup. Therefore if you want to run an et 55 offset wheel (popular OEM Porsche application), you will need either a 15 or 20 mm spacer to end up with an offset in the acceptable range (et40 or et 35)." and: "A 1" thick spacer would turn a common +40 wheel into a +15 wheel." this seems to support my theory, which is why I'm confused.

Offset is a property of a wheel and is relative to the width of the wheel. You cannot look at offset with out knowing the width you are working with.

If you constrain the wheel width to our OE 8" the following is true:

Higher offset = further in towards the vehicle

Lower offset = further out from the vehicle

A spacer will push the wheel out from the vehicle.

With a 1" spacer, you have increased the required offset for the vehicle since you have pushed out the mounting surface for the wheel relative to the rest of the car.

Spacers SUBTRACT offset from a wheel... is the wrong way to think about it because spacers don't bolt to your wheel they bolt to the car.

To use a spacer with a specific vehicle you need to ADD the thickness of the spacer to the required wheel offset for the vehicle.

e.g. Solstice uses +55mm offset wheel. If you use a 1" (~25mm) spacer you would need a 80mm offset wheel to retain proper wheel placement within the wheel well. +63 is the absolute lowest I would go for an 8" wide wheel.

If you start looking at wider or narrower wheels all of the above information will change relative to the wheel width.


Once again, please read this very informative Tire Rack Wheel Tech article on Offset.

[lil goat]

HOT damn I was right, do you have any idea how long it how long it has taken me to understand wheel offset, I used to lay awake nights thinking about wheel offset. I was actually able to explain it to my son the other day on his GTO. He is going to run the same size tires on his car as we do on 9" rims and we had to figure out how they would fit. He got the last set of the RE 01's from RMR.

[kwayne]

So after reading all the posts with the links, I went to my garage and on a piece of poster board drew my wheel w/centerline then took a piece of wood and moved it around.

I finally got what people were talking about-boy am I dense sometimes

So if anybody has offset questions PM me and I'll talk you thru my little demo

NOW I still have to make a decision on the rims

Thanks for your input

[Ben@tirerack]

Offset is a little bit counter-intuitive, glad you were able to get it straightened out.

[Kuprito]

Hi,

I need to know how much is the hub diameter to make wheel spacers.

Thanks

[Ben@tirerack]

The center hub of the Solstice is 65.1mm. Whenever you use a spacer, make sure you have proper engagement of the lugnuts on the studs. Usually safest to use longer studs.

[Kuprito]

Ben, you have a PM