Will these Wheels Fit???

[tonycharger72]

Spoke to a local Wheel Manufacturer in Australia - Performance Wheels and was told the following info,

 

Stock 1974 260z has a positive offset of 15+,

 

& i asked about the Superlites & the Challengers, and this is what he told me about the 15by7 & 15by8's,

 

Performance Challengers

15" by 7"

-13 offset, 88mm backspacing &

+8 offset, 108mm backspacing

15" by 8"

-9, 105mm

Performance Superlites

15" by 7"

12+, 112mm &

25+, 125mm

15" by 8"

-4, 110mm

Im more interested in the 8" wide rimms, can anyone tell me if i can fit the 8" rim on my 260z without modify springs or the guards?

[tonycharger72]

Ok, i have done alot of reading and have bothered alot of Performance Wheel folk

 

The Performance wheel folk seem to be of the opinion that i wont be able to fit the 15by8's on the Zed - but they werent 100% certain.....

 

This is what ive found out..............these are direct quotes lifted from other posts and Zed people in OZ,

 

"The centerlines I just sold were 15X8 with a zero offset (4inch backspacing) and no tire overhang on a stock fendered car with 225-50-15s on stock suspension with 1.5 inches of drop"

 

"125mm (5.0") Backspacing is perfect on 8" rimms with 225 tyres, but could just get away 4.5 (114.3mm),"

 

"My experience was it will be CLOSE! I ran 8" wide wheels with 245s with a 4.5" BS and I had a finger's width between the fender lip and the sidewall."

 

"I just put drag radials on mine. Use a 15x8 4.5 offset and they will fit. I have stock fenderwell, and it does not rub."

 

The above information seems to all point to needing 4.5" of backspacing if you want to use 8" rims on your Zed with stock guards and spring diameters, which means that i could probably just get away with using the Performance Superlites 15by8's and 225 tyres..........

 

Anybody got an opinion???

[tonycharger72]

No one knows the answer to this question???

[2126]

Tony, A search though the archives will enlighten you on wheel fitment for the Z. Basiclly, by taking a few measurements of your existing wheels and fender clearances you should be able to determine what will or will not fit. I'm running 17"x 8" in the front and 17"x 9" in the rear and have no clearance issues (my Z has been lowered 1.5" to 2" as well). Some of the tire/wheel manufacture sites provide a lot of info on figuring offset and backspacing too!

[tonycharger72]

2126, check the post i did about 2-up, you can obiviously see that i have searched this site - where eles do you think i got those comments from???

 

Some people have told me there is no way you can fit an 8" rim on a stock zed (stock springs & guards) no matter what tyre choice or offset, others like yourself say that you can and in fact are running 8" rimms,

 

This is what one Z-expert told me,

"125mm (5.0") Backspacing is perfect on 8" rimms with 225 tyres, but could just get away 4.5 (114.3mm),"

 

I know that this is wrong, the rims would slam into the spring perch if i was running 125mm of backspacing for sure,

 

But i will do as you suggest, take the measurements myself

[260DET]

When you are going for such a close fit it really is best to measure your own clearances. Check what backspace can be be run and go from there, its not hard to do and you can then be sure what will fit your car.

 

Its risky to advise someone on this subject unless you have recent exact experience. Because variations from car to car can occur.

 

For example, a friend of mine has a 260Z the same year as mine yet what wheels could fit our cars were different. Then he told me that his struts had been bent to gain some negative camber. Which of course changed measurements relevant to wheel fit

 

That same 260Z has just been fitted with the recently released eight spoke Wantanabe look alike Performance wheels in 8x15. The guards were rolled and he has coilovers, tight but neat fit on the front, a bit more room at the rear.

[tonycharger72]

This is a Tad off-topic, but 260DET i read somewhere in Hybridz that you were using PBR rear calipers on your Zed and a 4-spot caliper up front???

 

Be interested to hear about your brake upgrade mate,

[tonycharger72]

This is what i think ive figured out, anyone please tell me if ive got this wrong,

 

Stock 260z with 14by5.5 rims has

12mm Offset

81.85mm (3.22") Backspacing

57.85mm (2.28") Forwardspacing

and uses a 195mm wide tyre (195/70-14)

 

So if you wanted to go to an 8" rim and use a 225mm wide tyre,

& keep the centre-line of the rim exactly the same as stock so the offset remains stock,

 

Start with the rim,

5.5" to 8" = 2.5" (63.5mm)

divide this number by 2 (because you want to add equal amounts of increased wheel width to the inside and outside of the rim)

81.85+31.75 = 113.6mm of Backspacing,

 

So this means that if you use an 8" rim which has a backspacing of 113.6 (4.5") of backspacing you have increased the inside & outside of the wheels in the same exact proportion,

 

I took some measurements of my car and it was hard to be 100% accurate, but i figured that i had roughly 20mm either side for clearance,

20mm between the 195/70-14 tyre and the springperch and

20mm between the 195/70-14 tyre and the lip of the guard, 40mm of space total available,

 

Which would mean you should be able to run 235mm width tyres and it would just clear,

235-195 = 40

but to be on the safe side probably go with 225's, and should have no clearance issues,

 

Therefore,

You should be able to go to an 8" rim without going to coilovers and without lipping the guards and run 225 tyres

maybe even 235 (but this might be tempting fate) If

You have 113.6 of Backspacing on your 8" rim,

 

That is for an 8" rim (203.2mm)

113.6mm Backspacing

&

89.6mm Forwardspacing

 

& this also means that increasing to larger width wheels you increase the inside in exact proportion to the outside

[fastzcars]

Now, you do know that when a manufacturer saids an "8 inch rim" .That it's being measured on the INSiDE MOUNTING surface. In other words the wheel is measured without the tire and the distance between the "mounting flandges" So the outside width is actually closer to 9 inches, taking into account for the thickness of the insde and outside flandges. And that may vary from manufacter to manufacter, depending on type of construction( cast or forged). I think if you go to the http://WWW.tirerack.com . They have documentaion that clearifies all this. I hope this helps. By the way I too did have centerline wheels on my car with the stock suspension. They were 17x"7" with a 4 inch backspace. They cleared nicelly the stock body work.

[tonycharger72]

When i wrote my last comment no, but about 2 hours later a wheel manufacturer told me that exact same thing,

7" rim approx = 8",

8" rim approx = 9",

and so on..........

 

We live and learn

 

So now i know, for certain, there is absolutely no way in hell you would be able to fit an 8" rim under a zed unless you flared the guards or used coilovers

[Guest egmar]

I do have 15x8 rims on my race car with 9" cantilevered tires. fits no problem. now I want to replace at least one set of rims with lighter ones, than my current steel rims. does anybody sell or have any leads. this forum has already helped me to get a nice fiberglass front clip. thanks in advance for your help.

egmar

[tonycharger72]

"I do have 15x8 rims on my race car with 9" cantilevered tires. fits no problem"

 

Wow...........this is really starting to get annoying

 

Do you have coilovers?

Have you flared your guards?

Is the car lowered?

 

If no,

 

What is the wheel offset and backspacing?

[ZROSSA]

Tony, I have 16 * 7's but could easily go to 16 * 8's. There is room. Mines a 2+2 though. No flares, no coilovers. Might make a difference. The cars at a mates so I will get some dimensions for you on sunday. Looking forward to hereing what you come up with on the brake front.

 

Cheers, Douglas

[Guest egmar]

the fenders have flares about 5" in the rear and 6" in the front. front also has a 1 1/2 wheel spacer. coilover springs. tire outside diameter is only 22.6". I am not sure about offset. how is it being measured?

egmar

[tonycharger72]

"So now i know, for certain, there is absolutely no way in hell you would be able to fit an 8" rim under a zed unless you flared the guards or used coilovers"

 

egmar..........ummmm, you have flared guards and coilovers on your zed mate, i assume you mean adjustable coilovers with a smaller OD than stock springs when you say you have coilovers, if so, this means that with flares you have alot more clearance than a stock zed would,

 

If you have an 8" rim on your Zed (it actually means its a 9"), therefore,

 

If we start from the stock Zed wheels of,

14 by 5.5 (6.5) with a positive offset of 12+,

Backspacing stock = 94.55

Forwardspacing stock = 70.55

& 195/70-14 tyres,

 

There is about 20mm either side for clearance,

That is,

20mm untill the tyre hits the spring,

20mm untill the tyre rubs the guard,

These are approximations, but they are pretty close,

 

Lets say we want to keep that same offset and go to 8" rim (which is actually 9" approx) & 12+,

Backspacing = 126.3

Forwardspacing = 102.3,

 

You have increased you backspacing from 94.55 to 126.3, a total of 31.75mm,

&

forward spacing has increased from 70.55 to 102.3, again an increase of 31.75mm

 

From the measurements ive taken on my car with stock tyres, stock springs and stock guards with only 20mm clearance,

You run out of space on the inside by about 11.75mm

&

You run out of space on the outside by about 11.75mm,

if you use an 8" rim and the 12+ offset,

 

So lets change the offset,

 

We change the offset of the wheels - so it clears the springs on the inside for instance,

Take the offset back to ZERO which would increase forwardspacing by 12mm, and clear the springs,

NOW......

Backspacing = 114.3

Forwardspacing = 114.3

This would mean that you clear the springs by 0.25mm, but now you will have 11.75+12 = 23.75mm

(1" approx) of tyre sticking out past the guards, so now you need some flares,

 

Its the Same problem if you go back the other way and increase positive offset, your 8" rim will smack into the springperch,

[tonycharger72]

ZROSSA, see your in NZ mate,

 

Im pretty close to working out what im going to do with the front brakes, not 100% certain if ill use the wilwoods or use the R32,R33,R34 GTS or GTR Calipers, just waiting on a few bits of info before i make my final decision,

 

There was actually a bloke very close to me who was selling the following to suit a zed, the bloke used to rally his zed

Price is $AUD

 

Brakes

 

$4500

 

Brembo Front Calipers

Front Alloy Caliper Brackets (Bolts on Std Mounts)

Brembo Rear Calipers

Rear Steel Caliper Brackets (Bolts on Std Mounts)

New Pagid RS4-2 Brake Pads. Pads last aprox 12 rallies

Front Discs x 2 (295x28mm Slotted) VGC

Rear Discs x2 (280x28mm Xdrilled) VGC

Rear Alloy Disc bells

Ex-works front alloy hubs with anti-knockoff system.

Braided Lines. (Goodridge Street Legal.)

 

He also worked out a provision for using a mechanical handbrake, seemed like a nice setup

 

But ill let you know as soon as ive figured it out mate

[Guest egmar]

my car has a suspension set-up by carrera, which was the main sponsor when the car was turned into a racer many years ago. I do not know what the original size springs are, but mine look like 2" or 2.5" diameter. the backspacing on the 15x8 is 80mm and gives lots of room for wilwood superlites and the springs. as I mentioned earlier, the 9" tires stick out over the original by about 3". when I purchased the car it came with 350mm tires in the rear mounted on cracked carbon rims.

egmar

[ZROSSA]

TC72,

Measured the rims today. As I said before they are 16 x 7. Back of the hub mounting piont to the out side of the rim was 127mm. I am running 225/50/16 on these rims so they over hang a bit on both sides of the rim but there is no rubbing. I also have a 7mm spacer thats included in the above measurement. The closest point to rubbing is in the lower part of the spring mount and the tire. Not the rims. I dont think I would run a tire larger then a 235 on the front. I think a 8 or maybe even a 9 inch rim would work provideing you dont go past the above rim sizes. Hopefully I can put it to the test soon. Have my eyes on some 17 x 8 and 17 x 9 skyline rims that are on one of the local auctions. Might be needing flares after all.

 

Douglas

[NZeder]

This might help. I just sold/swapped my set of Compomotive ML (minilite look alike made in the UK). They were 15x7 -6 and 15x8 -12 so that would be measured outter rim to outter rim 15x8 and 15x9 (or there abouts). The tires are 205/55/15 front and 225/50/15 on the rear. There were not wide enough for my car (custom flares).

 

The car these are now fitted to is a 260z 2+2 with stock fenders. However for 100% clearance on the rear the lip should be rolled only in the top section. However there is more than enough room on the inside between the stock suspension and wheel/tire combo. Therefore I believe a 15x8" with 0 offset would fit with no modification to fender or suspension (I know these will work on the rear, the front might be close and may require mods to fit the 15x8")

 

I took some measurements from these rims before I sold them here they are with some calculation.

 

15 x 7" offset -6 total rim = 8". Backspace = 3.75" (using calculated = 3.764"). So 8" - 3.75" = frontspace = 4.25". These clear stock fender and suspension

15 x 8" offset -12 total rim = 9". Backspace = 4" (calculated 4.028"). So 9" -4" = 5" of frontspace. These don't fit the front too wide. stick out by 3/4" but will fit rear of 2+2 with slight lip rolling to ensure not tire rub (the tire I had installed have quite a rounded side wall)

 

So using this a 15x7" 0 offset will work on the fronts not a problem = 4" BS and FS. and 15x8" 0 offset will work on the rears with no mods = 4.5" BS and FS. But these might be 0.5" too wide for the fronts.

 

Here is a link to a pic of a 240z with Compomotive ML in 15x7" and 15x8" both with 0 offset this car has stock fenders.

 

Here are pic of my wheels fitted to a 240z with stock suspension and fenders with the - offsets they are a bit wide (these were for my car with flares but they just fit a stock 2+2, these appear to have a little more room in the rear, if the rear lip is rolled just a little to ensure no tire rub) Again these are 15x7" -6 and 15x8" -12.

 

you can see from the shot of the rear shows that the -12 offset makes them a close fit on stock fenders with a 0 offset this will move the rim in closer to the spring by 12mm (or almost 0.5" ) there is enough room to allow this (but not much more with stock spring diameter) Compare this to the photo of Dans Z above (blue car) with the 0 offsets and you see they fit much better.

 

Hope all this helps. Also this will help also. Years ago I purchase a set of performance superlites for my 240z race car in the following spec.

15x8 -2. I had 245/50 slicks fitted and the just fitted the rear of a 2+2 (they did not fit my racecar with stock fenders, it was a 240z, but they worked fine once I rolled the lip) with a smaller tire this should work but it will be very close depends on the car and the tire combo. They were too wide for the fronts but another Z club member purchased them from me and run them on his 260z 2+2 for a number of seasons (he had to roll the lips on the front, he also did the rears to ensure they were never going to be any issues, however this was not required)

[tonycharger72]

Ive done some more measuring, i spoke to SimmonsWheels Australia and they said i should measure from the rim and not the tyre for clearances, this is what i got at the fronts,

 

Fender - 44mm to Rim (5" rim (152.4mm) from rim 25mm -Spring perch,

 

Therefore have an overall space of 221.4mm, which means you run out of space to fit an 8" rim by 3.6mm, you need approx 225mm,

There just aint enough room at the front for 8" rimms, unless you change offset and lip the guards,

 

BUT................i have another question in regards to coilovers,

 

If you run smaller OD coilovers - the JTR book says that you only increase you allowed space by 9.525mm approx (1/4" to 5/8"), and people have said that with 5" of backspacing on an 8" will fit within the guards and miss the spring perch, so according to my calculations.........

 

5" of BS = 225/2 = 112.5 + 15 = 127.5 = 5" of BS,

Therefore an 8" rim with a 15+ positive offset would pretty much have 5" of BS,

And the stock 5" rim has a 15+ positive offset, so the track does not change at all, the outside width increases directly proportional to the inside width of the larger 8" rim,

 

So lets put in on the car with coilovers,

 

Stock -

44mm clearance to fender

25mm clearance to Spring Perch

5" rim with 15+ offset means 91mm BS & 61mm FS,

 

8" -

91mm BS increases to 127.5mm (36.5mm)

61mm FS increases to 97.5mm (36.5mm)

Clearance to fender (44 - 36.5 = 7.5mm)

Clearance to Spring Perch (25-36.5 = -11.5mm)

 

8" & Coilovers -

Clearance to fender (44 - 36.5 = 7.5mm),

10mm more clearance because of the reduced Outer diameter of the springs, therefore,

Clearance to Spring Perch (35-36.5 = -1.5mm),

 

Which means that if you kept the stock offset and went to 8" rims even with coilovers you would run out of space, from my calculations you would need to go to a slightly different offset - something like a 10+ positive offset for clearance, which means changing the track (although very minor change)

 

This also means that you cant really put more than 125mm (which i guess is close enough to 5" of back spacing) under a Zed that has smaller OD coilovers, therefore if you run 9", 10" or 11" rimms you would need to increase the outside of the rim in a greater proportion than you would the inside of the rim, thus changing the track of the car - which ive been told is a bad thing, but lots of people seem to do this and drive some really really fast zeds...............