Can you mount GRX FC-RX600 110/80 chainrings on a Tiagra 4700 chainset? Has anyone mounted these https://www.bike-discount.de/it/comprare/shimano-grx-fc-rx600-2x10-11-speed-chainring-961783 on a Tiagra 4700 crankset?
If they will fit it's a LOT cheaper than buying the whole GRX crankset.
No.
The Tiagra FC-4700 crankset has 110mm bolt circle diameter (BCD). The 30 teeth chainring of the GRX FC-RX600 has a 80mm BCD. It’s a “sub-compact” or “super compact” crankset compared to the “compact” Tiagra.
The larger 46 teeth chainring has a 110mm BCD and might fit on the Tiagra, but then you can just get the Tiagra chainring.