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Difference between HT and HZ rims

Hi Guys. Apart from the different spigot diameter and PCD, is there any difference between HT and HZ rims? ie width, offset etc?


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HZ & HT offsets

The HT rim will sit about an inch inwards iirc.
I have 3 HT-HG parts cars here with HQ-Z front brakes but they are still HQ PCD and i've no way of trying the std HT rim offset.


Thanks Dusty. Do you have standard HQ/Z rims on the HT-G cars? do they have any clearance issues? I'm trying to work out the best way to upgrade my HG brakes, and still keep the premier hubcaps, and don't want to buy callipers and new hubs to find that they won't fit.


HT with HQ brakes

I will go try sussing this more for you shortly and will post back later mate :-)


Thanks Dusty. Much appreciated


Dave's wheel worries

Okay, i had a look with what's laying around, "see here".

What have you got so far and what are you wanting to achieve exactly ?


Thanks Dusty. I currently have stock HG brakes and wheels. I would like to upgrade to HQ/Z Brakes. I have heard that people have clearance issues with HZ callipers on stock HT/G wheels. I would like to confirm either way before I go to the expense of buying HZ calipers and blank rotors, or HZ rims. I would prefer to keep HT stud pattern, but its not the end of the world if I have to change to HQ to put HQ wheels on. Based on your measurements, changing to HZ wheels would give me a 28mm wider front track than HT, sassuming the wheels are same width. If the HZ are 7" and HT are 6" (not sure of this), then that would add an extra 2 inches, would put me about 78mm wider, which may be getting a bit wide for the RTA. Basically, I am looking for the best way to upgrade my brakes, without having to go away from the premier hubcaps. Hope that all makes sense.


HQ back space

Hey dusty. You have the HQ backspace as 910mm in your shed. Should that be 91mm or 110mm?


HT rims on HQ discs

Sorry mate, should read HQ-Z 91 mm (i've edited that now).
I just measured another HQ-Z rim and that one measures 104 mm (almost identical spacing as HT :-).
Holden musta ran diffrent offsets through the HQ-J-X-Z range ????

I too need to get my head around all this, i'm using HQ rotors with HQ pattern but have to get some 15" rims made up....and Mr Wheelwright gunna ask me "what backspace ya want mate ?" FIIK ?, lol.
Guess i would like to get the backspace/offset spot on for the car but otherwise just go std HQ-Z spec, but having just found a second measurement for Q-Z..what is that anyway ?

Who's confused ?
I might have to go try knocking 3 of the studs out of a HQ disc that's fitted to a HT and try squeezing a HT rim onto it


So it would seem there's not a lot of difference between the HT and HQ/Z backspace. My major concern was that I have heard of people having caliper clearance issues when fitting HZ calipers and running stock HT rims, but no problems with deep dish rims. I measured the deep dish rims on my HT last night, and they are the same backspace as the standard HG rims, so I can't see this as being an issue.

As long as the hubs are the same length between HT and HQ, I reckon you would be best sticking with the HT Backspace.

I believe the HQ rotors have a larger spigot than HT, so even without the studs, you may not be able to get the wheel all the way on.

I am working on fitting a V6 conversions rack and pinion setup to the crossmember at the moment before I put the front suspension back together. Once I have all that done, and have sourced some HZ callipers and HQ rotors on HT stud pattern, I will let you know if it all fits.

You don't want to sell a pair of HZ callipers by any chance?



When you get your wheels made as him to assemble the centre into the rim but don't weld it. Take them home and trial them. I did this with my 15's I had for the EH years back.

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