When I collected my boat from Cardigan, I noticed that there were at least two other BR trailers that had been similarly converted to braked with 13" wheels. In case anyone needs to know what the various specifications are, I've put together the following information, mostly for my own benefit:
CLH Trailers (01994 230055)
Model: 18' RC (roller coaster)
Serial 091110C
GVW 1000kg
Nose weight 35-40kg
Knott braked coupling KRV20 A1
Knott-Avonride full beam axle assembly 1000kg width 1500mm
Type QB10C Part no.C68366.005
Serial 13/143487M/014
Knott Avonride X Series braked hub, part C24014
Brake type 20-2425
Brake size 200 x 50
Bearing kit 571005 Ø34 x Ø64 x 37mm
Grease cap 573004 64mm
Hub bolt (conical) 574015 M12
Wheel: Mefro RRA39063 (old 43698 105) 4.5J x 13H2, PCD 4 stud 100mm, internal hole diameter 60.5mm, 30mm inset
Hub bolt size M12, conical countersink
Tyre size 185R13C 96/94N FRT Radial tubeless (Compass brand)
Max pressure 65psi
Wheel bolts torque 65 lb. Ft / 88 Nm
Tighten bolts in sequence N-S-E-W
Max tyre load at 140kph (87mph) = 670kg x 2
Jockey wheel tyre 260 x 85, pressure = 30psi
Trailer length 7.95m including rear overhang
Maximum weight 1,000kg
Normal unladen weight 780kg (with registration plate and mast but nothing else)