you should be able to transmit more than that to a repeater, the idea with repeaters is they can receive much further distances because of the yagi array, then transmit it MUCH further because of a) the fact that they often push like 1000w, and they transmit on multiple, directional antennas
my 70cm HT i've used mostly short distance, but I've talked to people on FRS who were about 6 miles away, I can't hear them because FRS is legally max 2w, but they could hear me loud and clear, probably 1-2db over s9 my HT I believe is 5w
off the top of my head, I would say that your max distance to a repeater should be atleast double your peer to peer distance, at any given power, keep in mind that as you increase the power of your radio, the distance you can talk TO the repater can increase, however receiving from will be the same, but typically receiving isn't the issue in this case
N9XLZ here, licensed since the early 90's, general class with code. Not real active right now beyond storm spotting with Skywarn. But hope to get back on the HF bands in the next couple years. 73's Mike
km6kss checking in. been a technician since summer 2017. just bought my ranger a week ago tomorrow night. never thought i had much to say for ragchewing, but recently just getting into aprs. hoping to do much more dxing and camping in the truck. i'll be running a tyt th-7800, iirc. so... hi! nice to see this thread is still gasping.