What are the factory wheel offsets
 

Does anyone know the offset of the factory 18x8/18x9 370Z wheels? I've been poking around the forum for while and found the 350Z wheel specs a couple of times but haven't been able to find the 370Z wheel specs.

I'm looking at 18x8.5/18x9.5 wheels with offsets of 35. If that doesn't match the factory offset, what effect will the difference make?

I can't remember off the top of my head, but they are listed in the owners manual, chapter 9, specifications.

Thanks Triple. So there would be 8 mm difference in the front and 20 mm in the back because both wheels have a 35 mm offset. What effect would that have on performance?

In addition to changing the performance, I was wondering about adequate clearance for the break components.

I compared the Base, Sport and Nismo rims and noticed that, although the offset varies greatly in the rear (15, 30, and 23), it is consistantly large in the front (43, 47, and 40).

I was wondering if this related to the fact the front brakes are larger. Do you need the additonal offset in the front to accomodate the larger breaks?

higher offset brings them in closer, lower offset moves the wheel face away from the brakes.

The wheels you are looking at will fit fine in the front, maybe a little weak. you'd probably want a 15-25mm spacer in the rear.


http://www.rimstyle.com/images/conte...ned-offset.jpg
http://i23.photobucket.com/albums/b3...w01z71/bs2.jpg

Ah nuts. I thought I was grasping the concept but Red's reply only confuses me more. Perhaps a photo will help. I thought brake clearance was determined by how far the center hub I marked in red is elevated off the disk.

http://www.timothymichaelphotography...eCalipers2.jpg
And I thought offset was predominantly a measure of how much lip the wheel would have. For instance, in these two similar wheels below it seems the one on the right has a large offset because the mounting surface is pushed forward away from the center of the wheel and the one on the left has a smaller offset because the mounting surface is closer to the center of the wheel.

Wouldn't both these wheels have the same brake clearance based on how high the hub built into the disk is elevated?
And the left one has a deeper lip because it has a smaller offset?

http://www.TimothyMichaelPhotography.../TwoWheels.jpg

Help me out Red. Why do you suggest I would only need a spacer on the rear? If anything, I thought I might only need one on the front because of the larger brake calipers.

Confused in Pittsburgh,
Tim

Brake clearance is from the brake caliper to the wheel and is not only determined by offset, you need to take it on a wheel by wheel basis since different designs are "BBK friendly"

Also, a wheel can have no lip and a low offset and conversely a high offset and a big lip. It's all depends on the wheel.

How would I find out how much brake caliper clearance a particular wheel like the XXR 006 has?

I'm not familiar with the "BBK" abbreviaton. What does that mean?

I assume you're talking about how the OEM 18" 370Z rims have no lip yet offsets of 43mm front/15mm rear. The rear wheel has a noticably bigger "bloom" in the spokes than the front wheels because of the smaller offset. If I understand you right, to have no lip with a low offset you'd have to have spokes that "bloom" forward because a flat spoke design with low offset would have a big lip. Was that your point?

Bloom as you call it is commonly referred to as Concavity of the wheel.

Offset alone should never be used as a universal determination of whether a wheel can fit your brakes.

I was under that impresion till I read the forums. I'm grateful to knowledgable, helpful people like you who are willing to share what they know with others. Thanks for clarifying.

I think I've got the concept now. Last question, if a rim doesn't clear the brakes because its not setup for a BBK, a 20mm spacer would increase the available brake clearance of any wheel by 20mm, right? But it would also push the tire an additional 20mm out of the fender?

Yep.

No problemo at all, that's what we're here for :tup:

A friend of mine was told that the wheels he bought were BBK friendly and found out the hard way that even with a 25MM spacer his brakes still didn't clear the calipers and he had to sell his aftermarket brakes rather than run a 25mm spacer (would have been -15 offset, and way to aggressive)

Those XXR that you pointed out may clear your brakes but to be honest I'm not really a fan of them. If you're looking for an affordable wheel I would really suggest a set of Enkei's instead. They are alot more BBK friendly:

Enkei High Quality Wheels : Racing Wheels, Custom Wheels, Alloy Wheels,

I would suggest the RPF1's, the RPF01's, or the GTC01's which you can always have painted in the same finish as the XXR's.