Spacesaver wheel size - critical??

You are lucky all I have is a tyre inflation kit, being a plug in hybrid the electric motor and other gubbins takes up the engine compartment space so the 12V battery is located where the spare is on the IC versions of my car.

I had a Honda IC car like that, a compressor and bottle of gunge is useless by the time you've come to a halt on the motorway hard shoulder with smoking ruins of a tyre ...

Very odd! That looks like a regular tyre - so it won't actually save any space. If so, why limit it to 50mph?

My VW ID3 didn't even come with a kit - zilch! I'd been led to believe that it was coming with "self-healing" tyres. But they had changed the spec between ordering and delivery[1] so that it came with regular tyres

- but no-one had caught up with this. I only found out when I had a puncture.

I had a long dispute with the dealer and VW about this, and tried to get them to provide a space-saver spare - for which there is just enough space under the boot floor. They refused. VW don't offer space-saver spares for that model, but there are 3rd party ones which fit. They offered me a re-inflation kit, which I rejected.

In the end, they replaced the tyres *and* alloy wheels with the self-healing variety. [There were no self-healing tyres compatible with my original alloys].

Meanwhile, I had bought a 3rd-party space-saver for under £200. I would have settled for one of those from VW - which would have cost a lot less than 4 full-sized alloys and tyres!

My AWD car (KIA) was supplied with a narrow spacesaver - despite me making a full-sized spare a condition of the sale. I did get that full-sized spare, but it took around 5 months of hassling the dealer before it finally arrived.

A beef I have is that none of the several garages I've taken my car to for service and MOT have checked the pressures of the space saver tyre.

One garage did explain that the 10+ year old tyres on my wife's car were showing signs of ageing and would have been an MOT fail even though the tread depth was well legal.

I had an MX5 which came with a space saver. While I never needed it, the overall diameter looked quite a bit smaller than the normal wheels.

I mentioned this in passing to another MX5 owner and was told the advice was to fit the space saver on the front so the rear ( the car was rear wheel drive) wheels were the same size.

Also, our Outlander Hybrid didn’t come with a spare wheel. Plus, the drive system was ‘sensitive’ to wheel diameter. So much so, you were advised to change tyres in pairs - not just for tread depth / ‘grip’ but diameter.

When I bought a space saver, I hunted for one within mm of the overall correct dia.

So, in summary:

Normal car: not really an issue, at worst put on non-driven wheels.

EV / hybrid check if car is sensitive to wheel dia.

(Current 4x4 hybrid, a Rav 4, came with space saver. I’ve not checked with a tape but it looks a bit smaller than the normal wheels. )

The space saver in my RAV4 hybrid is an alloy one but not an alloy wheel like the others.

The one in Senior Management’s Aygo is steel - like the other wheels- but just a tad narrower from memory. The saving in space/weight/ cost must be naff all.

It is easy to see how an MOT tester could get this wrong.