curious about VP IRS wheel offsets

[jeepster]

I was searching through justcommodores to find the wheel offsets for various models. I noticed that the VP IRS wheels had a substantially different offset to the live axle.
This offset difference was less in the VR/VS. I guess the offset was changed to avoid tyres rubbing on the wheel arches or something else. But then if these wheels are on the front, the scrub radius would also be different. Did GMH rejig the front end, or was the steering affected on a VP with IRS?

 

[VPGTS076]

Nope....

 

[ducker85]

No just the diff was narrower. The 28P 15x6s on the front don't affect steering at all

 

[Cheap6]

The change in offset in VP/VQ IRS was used to widen the front track and yes, it does alter the geometry, but, with one exception, the hard suspension parts are identical to the earlier live axle cars. The top strut bush was moved back to increase caster, something that was also done on the live axle cars at the same time. The IRS is narrower hub to hub and the wheel offset altered solely to allow the wider front without changing the hard suspension parts.

The other two Commodores to have the front track widened in the same way were the VN GpA and SV5000. They have narrower (VL wagon width) live axle rear ends.

Why wheel offset wasn't used to alter the track on all models I don't know. I suspect it was due to the wheel bearing loads (perhaps on ute and wagon).

 

[Cheap6]

No just the diff was narrower. The 26P 15x6s on the front don't affect steering at all

The total track difference is 34mm; (43-26) x 2 = 34.

 

[ducker85]

Depends on what wheels are fitted but yes it's around 35mm usually

HSV VPs were 17x8 30P and VTs are 17x8 48P (48-30=18x2=36mm)

 

[UNLEASHED]

So if someones trying to flog a set of 20x8.5 and 20x9.5 rims with 43P are they still going to fit without spacers??
VPSS rims are 31P offset and the 43P offset VXSS rim rub on the rear without spacers but was told a camber kit WILL fix it?? :|

 

[ducker85]

So if someones trying to flog a set of 20x8.5 and 20x9.5 rims with 43P are they still going to fit without spacers??

There not going to fit even with spacers in the rear.

VPSS rims are 31P offset and the 43P offset VXSS rim rub on the rear without spacers but was told a camber kit WILL fix it?? :|

VP SS rims are 6 inches wide. The VX SS rims are 8 inches wide and should be 48P.

I have had VT Clubsport wheels and VT Inter on a IRS VP without a camber kit. Both 17x8 48P which rubbed the body. Used a 8mm spacer and cleared fine therefore changing the wheel specs to 40P offset. You a get 4 degrees adjustment with a camber kit from memory which should get the clearance without spacers.

My advice would be to buy new wheels and 8.5s alround.