I use a similar wheel on my Austin Healey Rally car. The size we uses is 15 x 5.5 but they make a range of sizes.
These are knock-ons (splined hubs with spinner) and the wheel name is Minator. They make bolt-ons also.
They are freely available in the UK from Specialist Car Products Limited
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Or if you want the original, look up Minilite here in the UK.