Bob_260

Thanks to everyone how responded back to my post. I'm convinced that this is not the way to go. I come away a little more educated on "Offsets" and "Wheel construction" . I really appreciate being able to tap into the knowledge and experience of the community! As a Newbie to the Z community the whole issue of what wheel/tire/suspension/car model combinations work with or,without Flare is more than a little confusing. I greatly appreciate your help I'll go ahead and get my tires mounted. (In response to one of the post: I didn't want to mount the tires if I was going to mill the wheels) As I mentioned originally I've already rolled the fender lip. If I a clearance issue, I may run a little camber in the rear or as suggested pull fenders to create the necessary clearance. Once I get the suspension back in the car I'll, try and post some follow-up pictures. Thanks everybody Bob_260

As I mentioned in my previous response, I'm just trying to understand where the additional material is coming from to support the different offsets the manufactures offer. I think you are putting forward a 3rd option that I had not considered. 3) I assume when you say "the barrel is usually shifted to increase or decrease offset.." You are referring to the center section of the wheel. (Sorry I don't know the terms for the various parts of the wheel). If the Spokes remain in the same location relative to the tire OD, then wouldn't the arch of the spokes have to change to reach center section? Wheels with large positive offsets would need much flatter spokes and negative offsets would need deeper spoke arches to move the center section in. That would mean that looking at the wheels you would see a visual difference depending on the amount of offset. Looking at the pictures I don't get that impression, but I could be wrong, I have not seen the wheels in person. But my impression looking from the outside a17x8.5 +4 mm offset, looks identical to a 17x8.5 +25mm. There are a number of YouTube clips showing offsets being machined down on a CNC milling machine, that's why I assume that they machined the backface to change the offsets The response from "thisismatt" regarding the depth of the lug nut recess being different depending on the offset, to insure sufficient thread engagement on the lug nuts was a good insight that I had not considered. Has anyone come across a website that shows the technical dimensions of the Rota wheels? I really appreciate the feedback and discussion on this! Thank you. Sent from my iPad

The basis of my question really comes down to the fundemantal question: If a wheel manufacturer offers multiple offsets for the same wheel, (+4mm, +10mm, +15mm....etc) where does the material come from to provide the different offsets? As I look at it there are only a couple of options: 1) to optomize cost they cast one base casting, with excess material on the center section, and during the machining clean up phase they machine the various offsets that they plan to offer to the market. This would optomize their casting set up cost and would give them the greatest flexibility during the manufacturing process. 2) the second option is to determine through FEA analsis what the minimum center section would be to handle the stress any more importantly the cycle loads, then cast evey wheel to that dimension. But if they did that they would have relocate the wheel spokes on every wheel to position the backface to the proper offset location. In other words. If they offer a +4mm offset wheel (like Rota) and a +10mm offset wheel, the spokes of the +10mm wheel would have to be moved in by an additional +6mm to generate the additional offset. When I look at the various wheels on the market, I don't get the impression that the spokes are moving. So this leads me to believe the wheel manufactures are utilizing option (1). So if I machine an additional +6mm, I'm not violation any of the original design considerations and therefore not risking a "wheel-off". I'm just taking the same material they would have taken during the original machining process. So where is the material coming from?

You are right I meant that I want to move the wheels in towards the strut to get the wheels is the fender well without flares. So I'd like,to increase the offset in the "positive" direction. Thanks for sharing the "Obligatory Datsun Photo"!

I'm a newbie to the Ratsun community, and I hoping to tape into the tremendous amount of expertise. I recently purchased a 1974 Datsun 260z and my first priority is to make sure the car goes where I point it and STOPS! So I'm upgrading to big disc brakes all around, adjustable Coilovers, bigger swaybars and polyurethane bushings. The big disc brakes have also meant that I need bigger rim. I don't want to add flares, but I have rolled the fender lips so I can put as much rubber as possible on the ground. Based on everything I've read and 8.5" wide rim was the biggest that would fit without flares. So I ordered a Rota RB's (17x8.5 with a +4mm offset). With all that said as background, here is my questions: 1) Obviously Rota has machined the rims down to a +4mm offset, how much more material can be machined off the 8.5" rims? Can I go to a Zero offset? -5mm -10mm? -15mm? 2) Other than than being mindful of the structural integrity of the rim are there any suspension or setup issues I need to be aware of?