Wheel Offsets question

[RS4-AL]

Hey all,

Been a while since posting since selling up. Very tempted to get back into another RS model shortly and liking how the prices of the 6's are finally coming down.

In the meantime I'm hoping for a bit of advice / clarity on wheel offsets as I'm about to put a new set on the Range Rover Sport. If MikeFish is around I remember he's a guru on offsets from previous chats?

I'm running the OEM 20's / 9.5" which I believe have an ET53 offset. If I move up to 10.5" the wheel is 2.6cm wider, so I assume it's 1.3cm extra on either side, meaning an ET40 would result in the same positioning in the arch on the outer edge, correct?

I'm aiming to get a flush fitment to the arches, the front wheels could sit an extra 1cm out to go flush, the rears could sit an extra 2cm to make them flush, so...

Based on 10.5 wide wheels, will that equate to ET30 on the fronts and ET20 on the rears?

I'm hoping I've done the calculations right, but it would be good to get some feedback.

Cheers guys.

[MikeFish]

Almost. You've gone the wrong way Al. To make the wider rim sit in the same place on the outer edge you need to push the wheel further in by 13mm not out so an ET66 is your starting point. Then take off 10 or 20 to bring the wheel out giving ET56 for front and ET46 for rear.

[RS4-AL]

Thanks Mike, sorry been away and just checked this thread. That all makes sense.

I'm looking at 10.5s with an offset of 38mm all round, based on another post I saw (below) where a wheel Shop over in the US ran 10s with an ET33 fine, would that equate to 10.5 with an ET38 also being fine then?

Ie 0.5" is approx 1.2cm, so 0.6 extra on each edge / difference between ET33 and ET38 is 5mm, so in theory 0.1cm difference in where the wheel will actually sit?

You can see in the image the fronts are pretty much flush to the arches and I'd say there's still a bit of room in those rears...

http://www.rangerovers.net/forum/showthread.php?t=16065