Diamond 969 Wrecker desert kit
 

Then Diamond wrecker who served in Africa had a desert equipment, bigger water pump and single tyres.

Who knows the desert tyre size ?

Menno Keizer

The single tires are listed as 14.00x20 12 ply. they were mounted on 10 inch wide rims.
Other desert modifications included a speedometer correction adapter and different front wheel stops and rear axle stops. I can't tell whether the front wheel stops are to limit the steering lock or the wheel travel.