All these comments about kicking tyres, hitting with torch, Ha what a load of rubbish.
Any medium size jet wheels can have a substantial pressure drop or be over inflated before becoming visibly different to the naked eye or by listening to the sound it makes!
It might be a reasonably effective method on a car but on an Aircraft, a calibrated tyre pressure gauge every time, TPIS is ok for a quick check but even that has to be cross verified with a gauge fairly often.
Back to the topic, Wish the guy the best of recoveries back home.