Hello, colleague has an x3 four-wheeler and would have to renew a tire. So can he put 2 new ones on it or is the regulation for all four-wheeled passenger cars so that you have to renew 4? Had read here in the forum that this regulation only applies to Audi Quattro…? Is it bad for the four-wheeler if you also drive HA 2 winter tyres and VA 2 summer tyres? Thank you