See the details on the ad above.
Jan-Willem (who, admittedly, is trying to sell them) says:
The Goldentyre went through several development stages, including expensive mould modifications. This under pressure from Chris Carr [7-time AMA champ, who worked on the development]. They came out really good and are certainly on a par with the Maxxis.
UPDATE: From Jan-Willem
These tyres are homologated in Europe and "E" marked.
Load and speed rating
for the front 130/80-19 (27.0-7.0-19) TT 67H
for the rear 140/80-19(27.5-7.5-19) TT 71H
The conversion was easy to return to standard.
[Note: Advert art by Ryan Quickfall]