Bongo Fury

I have four alloys on my van with 205/60/16 96H all round.

Then I have the stock space saver spare but I also have my old set of steel wheels. Two of these have 205/65/15 94H (thread wearing thin) on them and the other two have 215/65/15 100H (good thread).

Am I best off in keeping the space saver or would any of my steel wheels be any use as a spare instead?

Your space saver is most likely 15 to 20+ years old, a couple of people have reported putting an old one on and it bursting when lowered off the jack!

Yes that's probably true - so if it's the best option to keep the space saver, I probably need to get a new tyre for it.

My question was more aimed at which would be the best wheel to use as a spare given that none of them match with the wheels on the van.

If it's a two wheel drive I don't think the rolling diameter is that critical. However if it's 4WD then it is. The space saver as has been said will be old - I tried without success to find a replacement spacesaver tyre. If anyone knows where to source on that would be handy. Otherwise, yes a full size rim will give you the option of a new budget tyre to sling under the Bongo.

205 65 R15 are 0.8% smaller
215 65 R15 are 1.2% bigger
195 70 R15 are exactly the same size.

I can't quite remember but even with the 4WD, Mazda supplied front tyres that were a different diameter by around 0.8%
Of course the above calculations only apply to shiney new tyres.
Personally I'd use the 215 65 R15's if 2WD or fit a 195 70 R15 (buy a part worn one to match your presumably part worn tyres on your 16" wheels) if 4WD

I would use one of my old steel wheels as a very temp spare.....space savers are not ideal and probably have a different diameter anyway.

I'm now thinking I'll try and pickup another 16" wheel and get a cheap tyre on it and flog the full set of 15" and the space saver.

I've come across a suitable 205 55 16 for cheap

I would make sure it's load rated for the bongo, 16 inch are usually mazda car wheels and may not be strong enough for your bongo.