OK, maybe I am the only one with this problem. I (We) have had loads of pushchairs and we get flats all the time. Due to the dog walking we do and nasty paths we walk along our pushchairs always get flat tyres. The 3 wheelers are the best for us due to the terrain we have to walk across. Has anybody ever filled the tubes with tyre flat or expandable foam because that is what I am thinking of doing