With the Scout running on 225/50 R 17 tyres as delivered, can anyone advise whether use of the "full size" steel spare fitted with 205/55 R 16 will lead to any problems in the following scenarios:

1) short-term e.g. upto 50 miles run when getting a puncture repaired

2) longer-term e.g. whilst the standard wheel is refurbed or replaced i.e. more than a couple of days' use

Related to this question is also the aspect of position. Does it have worse consequences if used on the front or on the rear.

Finally, if there is a potential issue, which version of Haldex would be most affected.

I ask this because I've not seen anything regarding a warning, although I have hear about transmissions being "wound up".

The same question will also apply to the 4x4 where I think the tyre size is different giving a smaller circumference, so possibly less of an issue.

Thankfully the spare wheel well does accomodate a regular Scout wheel/tyre which is what I'm now using as a spare.

As the Scout gets the 16" full size spare steel wheel as standard I would very much hope that it is suitable for up to the 50 miles you state.

I certainly wouldn't loose any sleep if it ended up on the car for a few days...

Is the spare wheel really that much different in size though? Granted it's a different wheel size, but the tyre is higher profile which will make up most if not all of the difference?

I wouldn't worry about it personally, as long as it's the standard spare.

I'm actually running on 245/45 R 18 so the difference compared to the steel spare is more significant. Thankfully, due to a mistake by the dealer, for £45 I now have a knackered Scout wheel serving as a spare and the difference is less than between that and the steel spare.

You have 18's on your Scout? Any pictures!?

I assume that the rolling radius of the 16" spare is the same as the standard fit 17" alloy's due to the increased tyre profile hence it should be fine to use for a temporary spare.

Assuming your 18's are lower profile that the standard 17's to match the rolling radius then you should be OK...

You have 18's on your Scout? Any pictures!?

Not got them on this PC, but if you do a search on "Scout" + "Allroad" tyres you should find my previous post with the pictures.

I assume that the rolling radius of the 16" spare is the same as the standard fit 17" alloy's due to the increased tyre profile hence it should be fine to use for a temporary spare.

RR on 16s is over 3% less than on Scout tyres but I'm still unsure if there's any issue long term. I've always erred on the side of caution and kept tyre wear broadly the same through rotation. I've only replaced full sets of 4 rather than axle pairs so no front-back difference. Maybe I'm over-cautious.

Assuming your 18's are lower profile that the standard 17's to match the rolling radius then you should be OK...

Answers above, but sounds like Haldex isn't that sensitive. Assumed it to be like quattro where I recall some warnings about this issue (years ago).