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number crunching wheel offsets AGAIN!!!!!!

I am reposting this AGAIN!!!

It is quite important to get the terminology correct when ordering or inspecting new wheels (or second hand)...Offset and Backspace are different terminologys that describe the same thing....Offset is the distance between the rims centreline and mounting face...if the mounting face is exactly in the middle, The wheel has zero Offset....If the mounting face is closer to the bacck off the rim/mag, The wheel is said to have negative offset....Naturally if the mounting face is further towards the front,then the wheel has a positive offset...Older cars (LIKE OLD HOLDENS) use negativley offset wheels (DEEP DISH)....While newer cars (LIKE COMMODORES) use a positivley offset wheel...Backspace is simply the measurement from the wheels/mag mounting face to the back off the rim/wheel.....PCD- pitch circle diameter is the imaginary circle that passes thru the centre of the wheels mounting holes....Falcon has a 5 on 114.3mm PCD while commodore has a larger 5 on 120mm...PCD is independent of the number of studs,you could have 4,5 or 6 stud wheels on the same PCD....Finally the last one is the wheel spigot or centre bore (THE HOLE IN THE BACK OF THE WHEEL)...The wheels spigot must fit the hub perfectly as it carries the cars weight-NOT THE WHEEL STUDS AS MANY PEOPLE BELIEVE!!!!! This is why older-style mag wheels that use shank lug nuts are illegal (even tho you can buy them)SO IF YOU ARE WONDERING IF YOUR MATES WHEELS OF HIS COMMODORE WILL FIT ON YOUR H SERIES HOLDEN....THE ANSWER IS NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO!!!!!!!

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Great post MRHZV8. Maybe this should be kept at the top of the page for ever. It's scarey how many people seem to have Commy wheels on H cars.

Also, excuse my ignorance, but what does the shank lug nut look like?

Cheers, Steve.

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Agree with fitting 5/120 mm Commodore wheel is not right as also HQ-WB PCD actually works out to 120.65 mm which will put diagonal stress on each wheel stud. Offset for most Commodores( except VP independent rear which is 20 mm positive, the same as early 5 series BMW) is about 38 mm positive( meaning the rim centre is 38 mm outward fron the back of the bolt up face of the wheel). HQ-WB is about 6 mm negative. Working in the tyre & wheel industry this is the first time I've heard shank style wheel/nuts are illegal.
Most new wheels use a hub location ring that fits onto the hub & matches up to the wheel centre-bore. Duncan

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One the subject of what wheels fit what... I have an LH Rana and I see a lot of wheels advertised for HK/HQ/HZ/LH/LX and such like, but the fellow at the local tyre shop (who has an HX) told me H-series will not fit Ranas... but I'm also assuming Commode wheels don't fit.
Does anyone have a definitive answer?

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Some LH/LX's have been converted to HQ stud pattern. The SLR5000 and A9X both came with HQ stud pattern from factory. But other than that hq-wb PCD is different to LC/LJ/LH/LX/UC torana. Torana PCD is the same as early holden prior to HQ. Eg HK HT HG HD HR etc.

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A9X had Q stud pattern not slr's unless optioned with A9X code.

Redbeard

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The code being L34 ?

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L34's had the banjo diff that was torana stud pattern.
A9X had Q stud pattern.

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ONCE OWNED AN L34.HAD HQ STUD PATTERN.(FROM FACTORY).

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