Rota RB/RB-R, 4x114.3, 17", Z-Offset Wheels

[rudypoochris]

I think the guys with wats run 245mm tires, not sure though. I went to my brothers today and put the mock up wheel on:

 

Image 1

 

Image 2

 

Image 3

 

Image 4

 

Image 5

 

Image 6

 

So I set the mock up wheels with one side a 275/40 sizing and the other a 245/40 sizing. I did not try the fit on the back. I started with a -6 offset testing the 245/40/17 combination, it did not clear the rails at full lock, there was interference at the fender as well.

 

Image 3 illustrates the contact with the frame rail and the coilover perch.

 

I then spaced out the wheel to a -19 offset. This looked the best and seemed to work pretty well. Using this offset I achieved 3/4" to 7/8" tire to rail clearance at full lock to the right (image 4). Also note in Image 4 that this setup yielded 5/8" to 3/4" of space between the wheel and the coilover perch. The coilover perch is ~3.5" OD, can anyone tell me the stock perch OD?

 

In Image 5 at full lock to the right again, one can see the tire did not clear the stock front valance. It interfered 1"-1/4 maximum (max interference appears to happen at full lock, I checked other angles). Can someone with ZG flares chime in about how much more space they add in that region. Does an airdamn remove that turn in on the lower valance entirely? I think this amount of interference is probably acceptable with a car setup on flares and possible air dam. Not sure though.

 

Image 6 shows full lock to the right, the clearance is approximately 1"-1/4 tire to rail. Nothing to worry about imho. There is no fender interference stock at the back. It is only at the front where the valence is located.

 

All of the testing was done at full droop. The car has bumpsteer spacers (don't think this matters). The alignment is setup by eye and ruler right now, it is straight enough to roll with no noticeable increase in resistance. The width of the cardboard to simulate the tire is the section width. The section being the widest part of the tire (the buldge) thus in reality there should be increased clearance as the outside of the tire is skinnier. I would think a 255/40 tire would work fine up front with this -19 setup provided the front valance to tire clearance is not a pinch point. The 275 tire won't fit with out major modification or pushing of the wheel out excessively far.

 

The -19 makes sense and I think the tolerances should clear stock springs. The watanabe 16x9 fronts use a -13 offset. Considering our wheels would be 1/2" = 12.7mm wider this works out. 12.7mm/2 (two sides of the wheel) + 13mm. That would make a -19.35 offset. 240hoke said there was plenty of room with his 16x9 -13 offset fronts on a ZG flared car, this 17x9.5 -19 offset should work.

[dreco]

just to add.. i used to have a set of 17X8, with 5 inches of back spacing, and they just barely fit with the stock struts in the rear.. I ran a 235 tire, and rolled the fender a tad.. cannot go any bigger without flares or coilovers. 17's along, with more tire options will also be able to clear brake upgrades..

 

i'll find some more people

[bry593]

17x9.5 won't work very well on a Z. save yourself some grief and get 16x8 with a 12 to 15mm offset... this should clear everything on a stock or lowered z. ZX's could probably use a 9.5, as they have more fenderwheel than a z.....

 

this is based on personal experience with 16x8 0 offset on a '72 240z. this setup has 3/4" clearance on rear coilovers and slightly more on front coilovers (hence the 12mm offset for stock Z). unfortunately, with 0-offset, tires will hit front wheel arch (unless you have an air-dam), rear tires will hit fender lip on a lowered Z (even if you rolled the lip). stock rear height will not hit if you run 26.1 trim height and 200 lb/in spring.

 

anyway, that's the truth..... spend your money however you see fit..... personally, i dig the Rota RB and would have bought a set had they been available in 16x8 +12ET....

[Guest coyboy510]

I just came across this over the weekend and am very interested in a set for my Z. However, I have the same sentiments as someone in the thread about the size/offset combination discussed. It seems to still be unresolved?

The setup that I'd like would be for a Z running ZG Flares "without" coilovers. Im running Nissan comp springs with shortened strut assemblys. The offsets that I'd like someone to recommend would be the specs from the Watanabe site for ZG wheels (http://www.rs-watanabe.co.jp/matching/nissan.htm). I realize they aren't the same diameter, but can't we just use these values?

240ZG: (from the link above)

15"

F: 15x8.5 -6 (offset)

R: 15x9.5 -19 (offset)

16"

F: 16x8.5 -6 (offset)

R: R 16x9.0 -13 (offset)

 

Backspacing turns out to be: (determined by me...please double check math/conversion)

Width (in) Offset(mm) Backspacing (in)

8.5j -6(mm) 4.013779528(in)

9j -13(mm) 3.988188976(in)

9.5j -19(mm) 4.001968504(in)

 

Shouldn't we just keep consistent with what Watanabe did/does maintaining a 4" back spacing? Or at least for the folks that are wanting to run the ZG Flares.

 

How many folks are there now that want to buy?

 

Oh, I forgot to mention the the 17" or 16" diameter is fine with me.

[rudypoochris]

The 16x9.5 watanabes use a -19 offset. For our 17x9.5's, that is what I recommend after having made a mock up wheel, fitted it, and measured. I understand your worries though. There is no way to know until it is on. In any case, 4.5" backspacing (same as the wats) should clear a stock setup... earlier I asked for the stock perch OD (I have coil overs) if you have that dimension I will confirm it for you.

 

I know alot of people like to throw out numbers and imagine what it might be like based off of wheels that fit in approximately the same size. This is no good. As I posted earlier... the suggest 16x8 +12 which was supposed to be a safe size that would "same some grief" doesn't actually fit. I know because I OWN a set of 16x8 +10 and they already rub with a 245/50/16 tire. A +12 is only going to rub more.

 

The proposed wheels ARE going to require flares and possible snipping of the lower valance (shouldn't be an issue if your going air dam). Yes the offset will be greatly negative as well. This is not necessarily a wheel for the masses, but it is a great wheel that should provide killer looks and the ability to fit tires that other people just can't. I appreciate your size recommendations and information though. It is very helpful. After building a mock up and testing sizes I basically determined that the watanabe -19 is the way to go. Using a 17" rim we would have slightly more clearance as well since the struts point inwards. Just a thought.

[rudypoochris]

Here is a rendering (what Kim sent me) of a +4 17X8.5 RB. A -19 17X9.5 RB would have an extra inch or inch and a half of lip.

 

[Guest coyboy510]

Well...I have decided to bite the bullet and order 1 set of the 17" RBs from 18 Racing for my "STOCK" Z setup(no coilovers). However, I haven't decided if I want to go with 17x7.5 or 17x8.5. Here is where I'd like some input from you folks. Im 100% confident that the 17x7.5 will fit due to past experiences. Except, I'd like to get the 17x8.5 if I could but i am not confident they would fit under stock fenders/Strut assembly Spring. I am about 80% against and 20% for getting the 17x8.5 wheels. Anyone have advice or actual experience running 8.5J wheels under stock Z (not ZX as I know they will fit there) fenders/struts?

 

NOTE: You can still count me in for 2 sets of the 17x9.5 -19 for my Flared Z.

[Bartman]

Well...I have decided to bite the bullet and order 1 set of the 17" RBs from 18 Racing for my "STOCK" Z setup(no coilovers). However, I haven't decided if I want to go with 17x7.5 or 17x8.5. Here is where I'd like some input from you folks. Im 100% confident that the 17x7.5 will fit due to past experiences. Except, I'd like to get the 17x8.5 if I could but i am not confident they would fit under stock fenders/Strut assembly Spring. I am about 80% against and 20% for getting the 17x8.5 wheels. Anyone have advice or actual experience running 8.5J wheels under stock Z (not ZX as I know they will fit there) fenders/struts?

 

If you're looking for the biggest you can fit under stock fenders, go with the 8.5's. Look at post #3 in this thread: http://forums.hybridz.org/showthread.php?t=122754

[hughdogz]

Unless I'm wrong, they should fit a 280ZX. I'm also running the Tokico setup, and these really thick RCA spacers from Techno toy (not sure that matters). I have 8.5" width, 17" rims that use a spacer for zero offset. They are still 1.25" inside the fenders.

 

I have 4.25" backspacing now and the RB's would have 4" backspace (9.5"/2 -19mm). How far they stick out from the hub would be 5.5" (9.5"/2 +19mm) which would be 1.25" more than what I have now and that should work perfect.

 

I'm tempted to go with the 8.5" RB's because I know they'll fit and are available now...but just looking at my ZX, the rims could come out another inch or so...

[rudypoochris]

Well a 9.5" rim width is actually around 10.5" total since you need to add about 1/2" for each lip. Thus it is 10.5/2 = 5.25 - 19mm = 4.5" Back spacing and 6" front spacing.

[SHADY280]

i currently run 9.5" wide 17 diameter rims with stock suspention height, no rolling or cutting required. i ft 255/40r17 on them with no problem. huge lip on either side of the centerline. i may want to purchace a set of the rims, for the bob sharp racecar, it would suit it soo much. i may just have to bit the bullet for them, how long do we have to decide b4 its too late.

[rudypoochris]

Okay guys... Might want to start a new thread...

 

In response to your question though, since you asked. I currently HAVE 4 Rota 16x8 +10mm 245/50/R16 fitted Grids. They clear coilovers no problem and probably would clear stock springs. You would need to roll the fender slightly. There is rubbing at the rail as well. A 245/45 would probably fix this. Alternatively you could space out probably 5-10mm. So I would believe a +4 or +0 would be ideal in your case... Hope that helps. If you want my wheels + tires I am selling them for too much money. BUT I already filed out the hub bore to clear 280z hubs. PM me if your interested.

 

As for your wheels SHADY280, mind measuring the backspacing? I am really interested. From the inside lip to the mounting surface would be great to know. I would like that -19 double checked. I did build a mock wheel, but it is always best to be too sure.

[JustinOlson]

Here's what the 17X8.5 look like:

 

http://forums.hybridz.org/showthread.php?t=126343

 

Regards,

Justin

[texis30O]

I am interested in this set up HOWEVER I HAVE to have mine CLEAR stock suspension (right now) and I DON"T WANT FLARES I will ROLL my FENDERS.

can I get in on a 17X8.5 on all 4 corners or do I have to get 9.5's?

[rudypoochris]

I am interested in this set up HOWEVER I HAVE to have mine CLEAR stock suspension (right now) and I DON"T WANT FLARES I will ROLL my FENDERS.

can I get in on a 17X8.5 on all 4 corners or do I have to get 9.5's?

 

17x8.5 +4 offsets are currently available through Kim at rotawheel.com

[rudypoochris]

Is this for certain it will fit stock suspension and stock fenders (some trimming or rolling OK) 240-280Z?

 

That is beyond my knowledge. There are people in this forum who have had them, try a search, I forget their name and modifications. Personally a 245/50/16 16x8 +10 doesn't fit on my 240z with coilovers, but that doesn't mean much. So not sure if that helps.

[russ in va]

I'll throw in my 2 cents on fitment. I have these wheels in a 16x8 with 10mm offset. My car is (unfortunately) at stock ride height. When I test fit a set of 245/45/16's, the front sidewall was in sligth contact with the spring perch. The rear would have fit except for some contact with the body work in a severe bump. If I had coilovers and the car was low, the front would have been fine (cut off stock spring perch and using 2.5" ID springs). In the rear, significant fender rolling and possibly stretching would have been involved.

 

I am running 225/50/16's instead. I had to massage the stock spring perch with a sledge (you could say I smashed the spring perch flat where it would otherwise have been hitting the tire). Works great. I've been meaning to refit the 245/45's with the spring perch shaped the way it is now, I suspect they would fit. With the 225's I have no problem in the rear, but if the car was really low it might require fender rolling.

 

If you go with 17x8.5 +4's and run a 245/40/17, I expect the front will fit fine (have a hammer handy to beat on the spring perch if neccessary). If the car is stock ride height, the rear will probably be fine too, but if the car is low or you drive on rough roads you will need to roll the fenders and possibly stretch them a bit.

[rudypoochris]

Any color on rotawheel.com link is no extra cost. 3-5 months is correct. They told me 3-4 but it is always nice to have a margin of error.

[rudypoochris]

That is a good question I would assume the company would bill when they ship, but honestly I do not know. All financial dealings will be from you (the client) direct with the main Rota supplier for North America. I have just emailed Kim Bong (kimcosmic@juno.com, supplier) your inquiery, I will post the answer when I recieve it.

[rudypoochris]

The issue with the 8.5" fronts with 9.5" rears is simply that for Rota to bother making the 9.5" setup in the specification we request, they need to sell 100 wheels right off the bat to justify even bothering to make the mold. If we all went with 8.5" front and 9.5" rear we would need something like 50 group buyers. Now that IS possible if that is what people want to do, but I am not sure it is/I am not sure we have those kind of numbers. We could just copy Watanabe's offset/specs for the front. If we would be doing 50 anyway, that is enough to have a custom front offset too...

 

At the same time, we are so close now that I think it makes more sense to simply buy the 9.5" all around and then if there is enough interest someone (or I) can organize a wheel exchange for those who would like smaller fronts.

 

I will call Kim at Rota today and ask if this can be done in a 17x9 -13 easily with less than 50 people, and so on. Then of course I will ask you all what you think. Group buy proceeds as normal.

 

EDIT: The rep is going to inquire with the factory about the possibility of doing 17x9" -13 front and 17x9.5" -19 rear. Any information about this will be posted here. Initially he said it would take 50 sets, but it doesn't hurt to ask, they might be more flexible. WOULD YOU ALL BE MORE INTERESTED IN THIS OPTION (17x9" -13 Front and 17x9.5" -19 Rear)??? POLL IT UP TOP