Wheel offset, 7" 8" 9" Options

[Teknon]

What is the original offset for the stock wheels?

To keep the new wheel at the designed offset that came with the 5.5" wheels.

What are the offsets to 7, 8 and 9 inch wheels?

[Mueller]

(IMG:http://members.rennlist.com/1976c38/wheel_os_small.jpg)

[Mueller]

some people claim a 7" rim with a 23mm offset works on stock rear fender, I say baloney since it's never worked for me, I've always had to roll the lip and/or pull the fender out a bit...

I am running a 7" rim with a 35mm offset which fits under the stock rear fender, there really isn't any more room to go inboard towards the trunk since you'll hit the trunk wall and the trailing arm (I tried to install an 8" rim with a 55mm offset and that is what happened)

on another 914, I was running 8s with a 23mm offset but I had to bring the fender out somewhat

[maf914]

In my opinion, offset is a difficult dimension to deal with. Back space is easier to visualize. But like most things, I suppose if you speak in terms of offset often enough it would become easier to deal with. Or in other words, offset the difficulty! (IMG:style_emoticons/default/laugh.gif)

[Mueller]

In my opinion, offset is a difficult dimension to deal with. Back space is easier to visualize. But like most things, I suppose if you speak in terms of offset often enough it would become easier to deal with. Or in other words, offset the difficulty! (IMG:style_emoticons/default/laugh.gif)

it's an american thing verses the ROW, I guess we had to be different or "backspacing" was easier for those that don't do math too well (IMG:style_emoticons/default/smile.gif)

that being said, 5" backspace seems to be the ideal/max backspacing for our 914s

[Aaron Cox]

In my opinion, offset is a difficult dimension to deal with. Back space is easier to visualize. But like most things, I suppose if you speak in terms of offset often enough it would become easier to deal with. Or in other words, offset the difficulty! (IMG:style_emoticons/default/laugh.gif)

word! backspacing is the better way to look.

you can only go sooo far inboard... but the outer side (fender) can change a little (roll/stretch/flare)

112-120mm backspace is common as is mentioned above

[lapuwali]

Offset and backspacing essentially state the same thing: the postion of the hub mounting surface relative to the rim.

The main difference is that backspacing is always "positive", where offset can be positive or negative, depending on whether the mounting surface is inboard or outboard of the wheel centerline. Offset also doesn't change based on a change in wheel width, where backspacing does. On the front wheels, where offset affects steering geometry (scrub radii), this can be quite important. A wheel that's 0.5" to 1" wider with the same offset won't change the scrub radii. A wider wheel with the same backspacing will change the offset, and thus the geometry.

[maf914]

Offset and backspacing essentially state the same thing: the postion of the hub mounting surface relative to the rim.

The main difference is that backspacing is always "positive", where offset can be positive or negative, depending on whether the mounting surface is inboard or outboard of the wheel centerline. Offset also doesn't change based on a change in wheel width, where backspacing does. On the front wheels, where offset affects steering geometry (scrub radii), this can be quite important. A wheel that's 0.5" to 1" wider with the same offset won't change the scrub radii. A wider wheel with the same backspacing will change the offset, and thus the geometry.

That is a good case for using offset in lieu of backspace. Not only does it give you a quick check with respect to scrub radius, it also lets you know if you will be affecting the bearing loading relative to the stock wheel.

With 914's though, it seems that any significant increase in width will bring an decrease in offset and affect the scrub radius.

[mskala]

some people claim a 7" rim with a 23mm offset works on stock rear fender, I say baloney since it's never worked for me, I've always had to roll the lip and/or pull the fender out a bit...

I am running a 7" rim with a 35mm offset which fits under the stock rear fender, there really isn't any more room to go inboard towards the trunk since you'll hit the trunk wall and the trailing arm...

(IMG:style_emoticons/default/agree.gif)
36mm, the offset of the 6" common rims, is very good for centering in the
rear fender.

At least for me, I can fit the 40mm offset 7x16 boxster rims without hitting the
inner fender, with ~2 degrees neg camber even.

Mike, what rim do you have? ( 7" 35mm offset)

[kenikh]

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This should help...