Hey jbruce,
We completely understand, and wholeheartedly agree with your response. We have dealt with “offset” debate for many years, so, I wanted to shed some light on some things that we have learned when trying to pry the custom offset out of a custom wheel manufacturer before the purchase is closed…
When dealing with multipiece wheels, many things factor in to determining the proper offset, now, some of these do not specifically apply to the Model S (yet), but…maybe soon:
1) Aftermarket brake kit
2) Body Kit (Wide Fenders)
3) Desired Concavity
4) Desired Tire (Race Slick/Street/OffRoad)
Thus, based on the above mentioned factors, the wheel manufactures have informed us that there is a lot of R&D, custom CAD work, trial and error, etc…that goes into creating the perfect fitment for a vehicle if it is not “stock”…
Now, with that being said, if the vehicle is 100% stock, offsets “should” be readily available, however, offsets on multipiece wheels from the same manufacture could be completely different based on the actual wheel, if you take a look at the wheel lineup from ADV1, each wheel is slightly different, thus, each wheel, depending on size, will have a slightly different offset…
Lastly, your comments about 1pc wheels, from manufacturer’s such as Ray’s, is spot on! Rays for instance, takes more of the cookie cutter approach, and creates standard sizes/offsets by chassis code…so, yes, those sizes/offsets are known/published/etc…the only down side to this approach is if you start modifying your vehicle, and are in love with a certain set of 1pc wheels that only offers say 2 or 3 sizes/offsets…they may not fit, or require you to run spacers.
I would be skeptical of any brand that is unwilling to share the offset of their wheels. There's no way you can be an informed buyer without these specs. The offset and the width will give you a consistent idea of the lateral location of the wheel edges -- where the outer wheel lip lies relative to the hub and thus also to the fender. Sharing and benchmarking of what widths and offsets work is common on performance car forums and creates an informed community (the reason we are all here). Trying to be guarded about an offset is silly because it needs to be provided even at a wholesale level and it just takes the first consumer to get a set of wheels to measure the offset. You don't see some of the most well established wheel brands BBS, Rays etc. withholding offsets and saying trust us its proprietary, even though they often invest significant R&D.
As you point out you may also want to inquire about additional specs such as the backplate design, caliper clearance etc. Forgeline actually has a nice chart to help visualize the variables
Forgeline: Welcome to Forgeline Motorsports
