Saddo that I am, I once did a test to see what the maximum tyre wear was. Its 100 - and if you exceed that the tyre goes flat. However the grip is so low that you would make a pitstop to change them long long before they get that worn.
I think I've had a puncture as a result of accident damage (the wheel appeared to sink into the ground) but its much rarer than in GTR2 or RACE.
I've had many flats in the Escort! Diving down the inside at Le Mans and at Warwick Farm is not recommended! But hell of a lot of fun, and yes the handling is all over the place. You can't maintain any sort of pace with the flats either.