So, Heres the deal. I work for a wheel manufacturer. Im building either a 17"/18" custom forged wheel. But im a little not in the know about specs.
You work for the wheel manufacturer and you don't know about the specs? I know more about my Wrangler than I do my pathy. If you can build a custom aluminum wheel for my wrangler I can tell you exactly what I need, but not on my R51. But lets see if I can help anyway.
What exactly are you trying to accomplish? Are you trying to fit bigger tires or just get a different look? If its just for a different look I would replicate exactly what the OEM 17" wheel is. Same width, same backspace same everything. Be sure to keep it hub centric as well. No need to go through all that custom work and end up with an inferior wheel. If you are looking to put on a bigger tire, how big of a tire and how much lift do you have? The way I see it the only reason to deviate from the factory specs is make a bigger tire fit better than other rim alternatives offer. Even then I'm not sure a new rim is needed. Unless you want a big fat tire. Then just make something with less backspacing. Of course you will then have issues with the tire rubbing the wheel wells.
Personally, for my R51 I can't see running anything bigger than a 255/75R17. That is a full 32" tire. Which is a 1 1/2" taller than stock. I'm not certain but I think this will fit on the stock wheel without rubbing. If you want even bigger, then I would go with the new BFG AT2 in a 34x10.5R17. Due to the size of this tire, I expect you would need to have a little less backspacing to keep the tire from rubbing when you turn. So in short, the rim you need to design is dependant on what you want to run for a tire. I wouldn't just design a rim to have a different rim. You won't likely build one better than stock. But it would be different. If that is the case I would just build it exactly like the stock specs but with a different design. I'm sure your company has the specs on all OEM rims out there.
Let me know if they do other custom work. I really might be interested in a 17" rim for my wrangler. No body makes a hubcentric 17" rim for a '97-2006 Wrangler. At least no body makes one with a hubcentric design and 4.25" backspace.
