I think the shore rating would be very hard to measure, the rubber is so thin and the spikes are too small to be consistent. Possibly we could get a data sheet from each batch which would actually give a percentage of whatever goes into making the tyre. The vendor must have these other wise they would not know how to make the tyre. If someone then suspects there is a fault then the tyre can be tested to see what it contains, this is the difficult bit, you would need a gas chromatograph, not something that could be done at the track but still very possible to get a result in an hour, from the tip of a spike
Like has been said its not just soft or hard tyres its the actual composition that affects its performance.