Neil,
Many years back, while working with REME, we had a BMP-1 come in for engine repairs, ( don't ask....this was before the first Gulf War, so not war booty! ). When they ran it around the workshop roads, it did scuff up the tarmac somewhat, on turning. I know your intended is a Czech version, but reckon the tracks look the same. Also standing on a hard surface, there is very small area touching the road, but while on earth, grass, etc. then the weight would bear on all the track surface, so where are your ground pressure figures calculated from?