I print PETG at similar nozzle temperature as ABS (225 for PETG vs 230 for ABS in my printer), but at a bed temperature of 70C and at lower speed. PETG is more viscous than ABS, so you need to lower the printing speed to actually extrude as much plastic per unit of time as the slicers thinks it does. Increasing nozzle temperature to decrease viscosity leads to more stringing with PETG in my experience. Lowering printing speed works better.