To quickly get an idea what tire availability is in any size, I use the "search for tires by size" feature at two on-line tire shops.
On Line Tires.com/
Tires in the original European GTS sizes were 225/50R15 front tires, 285/50R15 rear tires. Tires in the the original rear tire size aren't available, everybody substitutes 295/50R15.
If we ignore racing tires and tires rated LT for light trucks I found 5 tires in the 225/50R15 front tire size, having H, V or Y speed ratings. I also found 5 tires in the 295/50R15 rear tire size, unfortunately all of them were only speed rated S. Selecting the same make and model tires in the front as you select for the rear is not possible in these sizes.