After an unfortunate episode of trailer puncture last weekend, I want
to get a spare for my decrepit, refurbished trailer. The problem is
that the PCD of the 4 hole mounting is either 90mm or 3.5" (more
likely given its age).

I can't find anyone selling 4-hole with a PCD less than 100mm. There
appears to be a 3-hole size that is 88.5mm, but obviously that is no
good either. The tyre and tube are fairly easy to get hold of, but few
places will repair a punctured tube, so I could do with having a spare
about the place.

Can anyone point me at someone who might be able to help.

Cheers,

Pete