Yes the Austone is loved by almost everyone that has tried one on a 1500. Sorry it did not fit your 1800 though.
Have you asked about sending it back for a refund? One member did not like how his Auston felt when riding and was able to return it for a full refund as I recall.
If the tire is supposed to be the correct size in width/height by the numbers but does not fit the bike they may give a refund on that also? If the numbers say it should fit, but it does not, then it's not really your mistake so they may refund?
Have you asked about sending it back for a refund? One member did not like how his Auston felt when riding and was able to return it for a full refund as I recall.
If the tire is supposed to be the correct size in width/height by the numbers but does not fit the bike they may give a refund on that also? If the numbers say it should fit, but it does not, then it's not really your mistake so they may refund?