This doc lists tyres/rims for commodores but I don’t know your SVZ so not sure what year your car is. In any case I thought the following may be close/useful for discussion...
Holden Commodore 2004 5.7
– Generation: III (VZ) [2004 .. 2007]
– Power: 335 hp | 250 kW | 340 PS
– Engine: LS1, V8, Petrol
– Center Bore: 69.5 mm
– Wheel Fasteners: Lug nuts
– Thread Size: M12 x 1.5
– Trim Production: [2004 .. 2005]
Tire | Rim[ | PCD |
---|
235/45R17 93V[ | 8Jx17 ET48 | 5x120 |
235/40ZR18 91W | 8Jx18 ET48 | 5x120 |
245/35ZR19 91W | 8.5Jx19 ET43 | 5x120 |
Your tyre placard on the drivers B-pillar will identify the standard rims & tyres and any optional rims & tyres (If listed). You should base any mods off the tyre placard sizes...
So if you had 8jx18 rims with 235/45R17 tyres, you could go up two diameter sizes, plus 2 as they used to call it. That means you could go to 8Jx19 so then the tyre must minus 2 steps in aspect ration to match the original tyres outside diameter, hence must be 235/35R19.... Then load rating must be the same or greater for the tyre width, so 93 in this example. Speed rating must be same or better, hence a V speed rating...
You can apply the same logic to the optional tyre so if 19 were listed as optional, you could also go from 8.Jx19 to 8.5Jx21 with 25/25R21 91W tyres
If you wanted to go wider, you can if they clear suspension brake and bodywork but you can’t increase track more than a certain amount... which I can’t remember off the top of my head...
BUT it’s illegal to go narrower rims than what standard for your model so if your car had 8” wide rims and your using a 225 tyre on a 7.5” rim, it’s illegal unless a 7.5” wide rim is available on your model... also, stretching a 225 wide tyre on an 8” rim may not be recommended by tne tyre manufacturer so it could still be defected...
So as a start always look at your tyre placard and base things off that...
Also read the NSW RMS doc
Guide to wheels and tyres which goes into legalities...