When you secure a load on a moving vessel you do not want any flexing, but a stiff load and lashing. Deflating the tyres will not provide this as the rubber will flex and the wheels might skid on the rubber as well. In addition I do not think that neither the tyres nor the rims will benefit from such treatment. Using wood blocks is fine provided it is located correctly.
Per
Partly my point Mariner, the wood blocks in the examples shown were (imo) most definately not positioned correctly and I can see a clear case for them shifting and leaving the straps loose, take a look again at the pictures and tell me what you think