All range claims of over 1/4 mile or so with FRS and a mile or two with GMRS radios using rubber duck antennas are bogus. With a decent “real” antenna fed with low-loss coax mounted 30-40 ft high you could reasonably expect to get 10 mile radius coverage on GMRS with the typical radio. Add a yagi (which you can easily make out of hardware store materials) and yes, 35 mile range is probably possible. The problem with the advertising is, they omit about 90% of what I just said and that just pisses people off. This ain’t rocket science, but it is radio science.
I have used an FRS radio effectively at over 2 miles.
From a mountaintop, looking at where I was trying to communicate with.
Step back in the tree-line 60 ft, fergetit.
I don't know anyone today that knows what a Smith Chart is. But there you go.