The mudguard comes from a trailer manufacturer called Peak Trailers.
Outer Dimensions are approximately
L 85cm H 45cm W 25cm.
As you are in Switzerland it would be worth trying to source locally as Charlie has said, postage charges were horrendously expensive.
From their website under plastic mudguards is a
datasheet. The nearest version I can find listed has dimensions L77cm x H34cm x W22cm and is for tyres 145-175 x 13". Is this the one you used?
