yes gary i too feel your pain. i have been looking for low profile 13inch tyres for a while and the best bet is what you call the 19inch variety, or the 50 series. they would set your gearing and speedo out by heaps but they are freely available due to the use on mini minors all the way up until 2002 in the uk.
falken and someone else also make them, the only thing stopping me is the $$$. they aint cheap.