Custom Made Wheels????

[DeeAitch]

Sy is correct

The wheel offset is the distance from the hub mounting surface to the centerline of the wheel

Therefore increasing the rim width will not allow a reduced offset as any change would be symmetrical about this centre line. All assuming you select a tyre profile which keeps the rolling radius ( & the gearing) the same and you are trying to keep the tyre contact patch in the same place Lotus intended.

Now if you were really clever and knew the angles of steering axis inclination (SAI), camber (which we do know) and loads of other dimensions you could probably calculate a new offset / rim Dia / tyre profile combination which would keep the centre of the tyre contact patch where Lotus wanted it to be! Then you are into loads of other areas such as Ride quality, un sprung mass, steering effort etc etc.

So you now have an insight as to why those Engineers at Lotus are held in such high esteem – or did they just get lucky, again and again and ……..?

I think we have ‘negative’ scrub radius – normal on FWD anyway. In other words the centre of the tyre contact patch sits inboard of the intersection of the SAI and road surface. Decreasing the offset, without other changes, will move this towards zero or even positive scrub radius see here for some good basic info.

A bit off topic but does anyone know of a simple way of measuring the castor angle / scrub radius?

[GeoffSmith]

So isn't the simple answer to correct for wheels with a smaller offset to add a spacer (and longer wheel bolts)?

[DeeAitch]

So isn't the simple answer to correct for wheels with a smaller offset to add a spacer (and longer wheel bolts)?

Sorry Geoff but the offset goes inboard so you either need wheels with an offset greater than 60mm or 'negative' thickness spacers

[GeoffSmith]

Thanks Dave. Of course it is.

I'll stick to electronics where current is electrons flowing the wrong way - hell of a lot easier to understand!

[DeeAitch]

I'll stick to electronics where current is electrons flowing the wrong way - hell of a lot easier to understand!

Is that the "negative is actually positive" thing they got wrong all those years ago? Or was that a myth

[51mon]

Just a long shot here, isn't it the case that all Porsche wheels have the 63mm negative offset that we want? Yes they do have 5 studs but if we went along with Brian’s plan it would only be the centre section that would need to be manufactured as the Porsche rims could be used.

51mon

[Monty]

ours are 60mm positive offset