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Acceptable + size offset


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Hi. Please forgive my newbie question. I know the original Z offset for 70-73 is 0 at 14x6. I should be able to use a 17x9 rim with ZG flares and coilovers at 0 offset for the front, please correct me if I'm wrong. What I'm really wondering is if I can make a 17x 10.5 with +15 offset work? If not, is there a minimum + size? Thank you for your patience and any info you can give in advance.

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Thank you. A searchin I will go. No sarccasm intended. Its just that I stopped after page 17 because everyone had spoken of -19 offet, etc. Unfortunately no one spoke of any plus sizes except through the use of spacers for the use of more modern types of wheels made today. I really like the classic look of a deep dish, but would like to try it with a larger wheel like the Domestic guys are doing now. Thank you again for your input. :) I'll keep looking.

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That's great news!!! A friend of mine found some pretty trick wheels that are in +12 and + 15! I've read about some people going all the way to a 9in. wide wheel in the front. That's really cool. My Starion had the GT wheels at 16x9 front and 16x10 rear. I miss that car. :( Thank you very much for the info. Now its time to look for some 17x9 front and perhaps 17x10.5 rear wheels from Japan!

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The stock 14" steel wheels on each of my 1977 280Z's were 5.5" wide and had a '0' offset.

 

As to the original question. The only way to know for sure is to set the car up and then get in and measure it. Every car is a little different by the time it goes through several owners, maybe a couple accidents, and some modifications.

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FYI... I ran 10" wide wheels front and rear with a 5.5" backspace. I was also running 2.250" OD coil overs so with 2.5" OD coil overs 5.25" backspace will work. Regarding wheels, you can get anything custom made through Kodiak, Kiezer, Jongbloed, CCW, and Bogart.

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Thank you everyone for all your input. :) I really hope I can find a car to start on. Off the subject. I have 3 Nissan 240sxes. My favorite one was hit by a drunk driver while she was parked. Would any parts be salvagable for use in the Datsun 240z?

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The starion wheels have like a 1mm larger center bore than the Z hubs. Your really lucky to get a set of those for the price you did, I just purchased a set (like 10 min ago) and am paying almost $500 shipped. I will have a spare pair of the rear 8" wheels if you are interested in playing with them. Im in everett BTW.

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Guest aussie260z

Shisho,

 

"I don't think you're going to be able to run +15mm offset on a 10.5" wheel."

 

What Auxilary said is right mate,

 

If you want to run a 10.5" wheel mate, just for the front, with stock suspension you only have 115mm to 120mm worth of clearance before your wheels will start to rub on your suspension components, so you would need some pretty serious flares on the front of your zed as you would be running a pretty large negative offset, id guess something like -30 to clear your spring perches, wheels would probably poke about 3" past your guards, maybe more..........

and a 15+ offset wont work with wheels this wide :-)

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Hmmm. What if I use ZG fender flares with complete coilover suspension to fit a 10.5 in. wide rim with +15 offset, what about +12? I'm willing to change to a 9.5 in. wide rear rim. Will a +12 offset with the above mentioned mods allow for this? Thank you everyone for responding. :) The rims I'm looking at are not available in America, so no test fitting :( I'm flying back to Japan in January and would like to purchase these rims with confidence they will fit.

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The + offset wil not fill out the flares. Your wheels will be too inboard. Skip the coilovers and get the wheels with a -19 offset and the flares will be filled out and they should be fine with the stock set up strut tube. A +12 offset would give around a 5.75 back space which would be too much with coilovers according to the previous post. The max offset for inboard clearance would be 0 (5.25" BS)with coilovers and -19 (4.5" BS) with the stock suspension.

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With coilovers you will buy yourself probably about 10-15mm worth of clearance, this would mean at the front of your zed that your allowable back-spacing for your wheels would be somewhere around about 125-135mm (5" to 5.5") max,

 

So if you have a 10.5" wheel and have 5.5" of backspacing this would equate to still running around about a -10 to -15 offset with your wheels to clear your suspension, a 12+ or 15+ offset with a 10.5" wheel just aint going to fit on your zed, even with coilovers,

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Bummer... :( I'm really trying to go 17in. possibly 18in. in the rear. It seems very hard to find lightweight rims in even +0 offset. Can anyone reccomend some rim chioces that can achieve my goal? Looking to maximize both front and rear wheel width, using ZG flares and coilover suspension. Using 17in. wheels. Thank you everyone that has responded so far. :) The sharing of knowledge has been most appreciated.

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About the widest tread width that has been made to work well on a 240Z (road racing and autocorss) is a 12" medium or soft compund racing slick. I know some folks who have tried 12" wide DOT-R rubber and it was difficult to get the tires hot enough to work well. I know that sounds funny, but tires are designed to grip the best in a fairly narrow temperature range. A 10" wide tire that's "in the zone" will grip better then a 12" wide tire that's too cool. Bigger is better only up to a point.

 

Also, the 240Z strut suspension needs tire sidewall to help with compliance. The suspension has a noticeable amount of stickyness and friction (stiction) and tire sidewall helps grip by absorbing small road impertections that don't overcome stiction. If the tire complinace is not there, those small road imperfections cause the tire to lose a little bit of grip. Enough of those imperfections and the tire skates.

 

Right now I know of no one racing a 240Z that has been able to make 18" wheels and tires work well at an autocross or on a road race track. You would need some pretty sophisticated dampers and a friction free suspension.

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"Also, the 240Z strut suspension needs tire sidewall to help with compliance. The suspension has a noticeable amount of stickyness and friction (stiction) and tire sidewall helps grip by absorbing small road impertections that don't overcome stiction. If the tire complinace is not there, those small road imperfections cause the tire to lose a little bit of grip. Enough of those imperfections and the tire skates."

 

John - so sticking with say a 16" rim and having a decent amount of tyre sidewall instead of going with a 17-18" rim with less sidewall to no sidewall would actually make your zed quicker for the reasons you listed above???

 

I know its probably pretty hard to say a definitive YES or NO to my above question, but all other things being equal, ie........identical cars, just different wheels & tyre sizes.............

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I'm running 16x7 wheels with a '0' offset with stock springs (stock ride height)and no flares. I've run both 215/55-16 tires and 225/50-16 tires. The 225/50-16's actually fit the fenderwell better. In either case, however, I should have had a +5 or 10mm offset to really fit right. With only coilovers it would be relatively easy to run 16x8" wheels (+15-20mm offset) and 245/50-16 tires on all four corners. The 225/50-16's seemed to perform pretty decently on the track. I was more limited by braking (toyota upgrade on front and drums on rear) and body roll (stock sway bars) than tire adhesion. I've since upgraded the brakes but the sway bars are still stock.

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John - so sticking with say a 16" rim and having a decent amount of tyre sidewall instead of going with a 17-18" rim with less sidewall to no sidewall would actually make your zed quicker for the reasons you listed above???

 

It depends on the sophistication of your dampers, how friction free your suspension is, and the condition of the track you're racing on. Here on the west coast of the US the race tracks are bumpy. In Europe and to a lesser degree the east coast of the US the tracks are smooth. In my case, I spent close to $14,000 on my suspension and wheels and I went with 275/45-16 tires. If I was running on smoother tracks I might have gone with 275/40-17s instead.

 

Remember, the suspension on a 240Z is not a very sophisticated design. Just because an E46 BMW M3 can run 18" wheels with 30 series sidewalls doesn't mean it will work on our cars.

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