Sorry all I know this can be a painful question.
My car is a ht with factory 10 bolt and lowered with not tub work and no lipped guards.

I put wheels on the back as follows
7 inch rim with 4.5 backspace.
215/60/14 tyres.

Clearance looks ok against the quarter and plenty of room on the inside.

I'm moving these rims to the front and buying wider for the back.

Back will be 8 inch rim with 5.0 backspace
245/60/14 tyres or
265/50/14

Calcs tell me the rim outer will be similar but inner will be 1 inch close which is fine as theres a bit of room.

What are your thoughts. Will they fit with no scrubbing ???????

Cheers for that. I specifically put the 215/60/14 on the back first to get a feel for clearances. Dury is still out on quarter clearance until I get some weight on it but I think it will be ok. Inside clearances seems to be heaps. I'm talking over 50mm. On width alone it looks like the 265 would fit so I'm wondering if it's worth a try and if know good get the wheel backspace increased.
Or just go 245 as planned. Will still look good.

Track is tyre/wheel centre to centre. So by increasing width by 1” and backspace by 0.5” your track remains the same.
To keep the outside edge the same with 8” you would need 5.5” backspace. Which would be possibly illegal as you will be reducing your track by more than 25mm, However you could argue you would still be within 25mm of HK with 5” rim track.

Edited by user Saturday, 18 May 2019 9:48:25 AM(UTC)  | Reason: Not specified

245/60/14 is a pretty big tyre too. Can you get a 245/50/14 still? Or try a 235/60/14 maybe?

Just watch your track, can’t change by more than 25mm. I reckon you'd get away with using the HK 5" wheel track as a start, so then you already have 1" to play with (0.5" more offset per side). You'll just have to check that on a HT-HG you are allowed to use the HK track as your starting point.

Starting with HK 14x5" these have an offset of 1.69" (1 11/16") (for reference the other extreme is HT 14x6 (or HK 14x6 with 1/8" spacer) which is 1.06" (1 1/16") offset).

7" rim with 5" backspace is an offset of 1".

So to remain within the limits of self-Certification (ie not requiring an Engineer's Certificate) the maximum offset you can go to, in order to keep the track within 25mm of the original HK track is:

1.69" + 0.5" = 2.19" (2 3/16").

On a 7" rim this is a 6 3/16" backspace.

If you are going by HT 14x5" original track you have 1" extra in track width, thus have 0.5" less in maximum backspace, so in this case 5.69" (5 11/16") backspace maximum.

You can Engineer it for more track change, but when I spoke to my Engineer a few weeks ago he said they are now directed to no longer be allowed to change track by more than 25mm using original diff width and bearings. You can Engineer to change it by having a shorter rear axle or by using rear wheel bearings designed for larger offsets. For example my HK's 9" is 40mm narrower than the original, and it has HQ-WB wheel bearings. So my track min and max are governed by the calculation around the min and max offsets of all wheels available on HQ-WB (which all vary from the 14x5 to the 14x7 Polycast and WB 15x7) plus the subtraction of the 40mm in the housing and axles. Thus I have a range of tracks I then have to stay within 25mm of the min and max of that range. I'm pretty sure you also have a track range on HK-HG as HK 5" wheel track is 1.25" narrower than the HT 6" wheel track (which is the same as HK rear with 6" wheels with 1/8" spacers). But you need to confirm you are allowed to use the HK track with HT-HG.

Note that as I'm using Imperial measurements the maximum backspaces I have given you are slightly out as there is 25.4mm in 1" and the rules say 25mm track change so technically the actual maximum backspaces above are 0.2mm larger than reality.

Edited by user Thursday, 23 May 2019 9:27:46 AM(UTC)  | Reason: Not specified

8” with 5” backspace is an offset of 0.5”.

That is 2” offset so track will be within 25mm of original HK with 5” rims but not HT-HG.

This is why I stuck with 15x6 front and 15x7 rear and 215 and 225 tyres. I don’t want rubbing or body mods. Mine is stock HK GTS ride height at the rear though but I have to have it 20mm lower at the front as that is the highest the Rodtech front end sits.

Same tyres I think will go on mine once all done, they look good with Warwick Yellow!

I was going to use 15x6 front and 15x7 rear Pontiac RallyII, which are 3.875” backspace on the 6” and 4.25” backspace on the 7”. However by the time I get them rolled to ensure round, blast and paint them it adds up. I can buy new Olds SS1 rims in 15x6 with 4” backspace and 15x7 with 4.375” backspace for about $335each inc GST. The extra 1/8” backspace helps on the front as it gets me back to within 25mm of HK with 6” wheel track. Rears are only 1/8” more backspace too. It looks like these may take HQ-HZ centre caps too.

Edited by user Friday, 24 May 2019 3:46:09 PM(UTC)  | Reason: Not specified