Newbie question - wheel/rim size

[roy4matra]

Clarification please...
I'm asking:

Is "Offset" the distance between the face of the flange where the wheel is bolted and the centre line of the wheel rim?

If so I can measure it easily.

Andy

Yes it is Andy.  Even the RT manual does not give the offset or ET figure, but since the front suspension is very similar to the Murena where the correct offset is 29mm, I suspect it will not be much different.  As someone else (mimu?) stated, alloy wheels normally have the figures cast or stamped in them, so check your original alloys.

Roy

[mimu]

Where in the garage last night, numbers which I thought was ET was just sizes.
So some research to do.
tbc

[GP]

Something of interest E.T. / Wheel  Offset calculator

http://www.oponeo.co.uk/advice-and-tips/wheel-offset-calculator

[mimu]

Here is a simple guide how to calculate the ET:
http://forum.jdmstyletuning.com/showthread.php?20793-How-To-Measure-OFFSET-on-your-Rims

I will of course measure my wheel next time I'm in the 'cave'

[roy4matra]

Something of interest E.T. / Wheel  Offset calculator

http://www.oponeo.co.uk/advice-and-tips/wheel-offset-calculator

Whilst this is a useful little on-line wheel calculation tool, it suggests that it is perfectly alright to go changing the offset as long as you can fit the wheel within the body or it won't stick out too far.  The whole purpose of the wheel offset it to keep the centre line of the wheel aligned with the centre line of the wheel bearings in the hub.  If you change the offset, you put a torque loading on the bearings which they were not designed for, and they will wear and fail prematurely.

The calculator is quite useful as it shows the displacement of the centre line as you alter the offset.

The aim when fitting different wheels is to keep the offset the same or very close to the original to minimise the twist effect on the bearings.  On a car with easily replaceable wheel bearings, I suppose it would not matter quite as much since they could be replaced regularly; but on a Bagheera or Murena where they are a big job to replace you really should not be changing the offset.

Roy