Most family cars face their toughest test at the end of a weekend, not the start of it. The school run and the motorway present little challenge. It is the final stretch — a farm track leading to the campsite, an unmade lane to a country pub, a field serving as overflow parking for a local show — where road conditions change. This is where 4×4 tyres either perform as intended or fall short, and there is little room for compromise once wheels begin losing grip on soft or uneven ground.