So my van has been sitting around for quite a while, but thankfully has just passed 'her' MOT

However, there are advisories about the tyres: 'Tyre slightly damaged/cracking or perishing Nearside Rear'; and the same for the Offside Rear. The current 'shod' is Avon Supervan A4-75 but I'm told Avon is no longer producing these or may not now even be trading!
Your thoughts and recommendations for comparable/suitable tyres will be very much appreciated, as I do want to attend to this before 'we' go trundling anywhere again.
Thanks in advance