For the iX with Tyres.co.uk, Vredestein Ultrac and Nexen N'Fera Sport are available options for BMW's 20-inch wheels and come in 235/60 R20 108H XL. Before purchase, ensure to check the registration and driver side door placard as other iX wheels have different approved dimensions, load, speed, and XL specifications.
Check the BMW iX driver side door placard. This placard has the approved combinations of wheels and tyres for the iX. It also has recommended tyre pressure and loading, and together these make up the approved specification.
In most cases, the BMW iX would not need to have all four tyres replaced at the same time. Since the BMW iX has an xDrive all wheel drive system, replacement tyres must at the very least be of the same design and manufacturer. It would be ideal to use the front and rear approved values. Match and replace axle tyres as a set.