Thank you! I will try that this weekend.
If the radiator car were not holding pressure the coolant would boil during normal operating temperatures and you would experience coolant loss.
Here is the front bumper setup. The winch has been removed but had no affect on the overheating issue.
The part you mentioned about cutting back on power due to overheating would concern me a lot. That often means issues going on with rings/cylinder walls/compression.
This is just my own personal opinion, but if it were me I think that I would pull the spark plugs and run a compression test. Lowered compression even on one cylinder can cause overheating to some degree and if there is a mechanical fault you do not want to spend time and money on symptoms rather than cause.
You could also connect a vacuum gauge to an intake port as a precursor to running a compression test. The gauge reading will vary based on altitude for instance but a needle reading should be in the 18 to 21 range with the needle remaining rock steady. From the pic looks like some rugged terrain and a bit of altitude to me. Also looks like some fun boon docking dirt bike territory⊠
Could the oversize/overweight tires/wheels be putting more strain on the tranny, therefore more heat is produced there? And because of the higher gearing caused by the oversize, the engine (and water pump) are turning at lower RPM, so the coolant flow is lowered?
So excess heat produced + less flow of coolant through the radiator = overheated engine.
Oversize/overweight wheels/tires have many downsides, and maybe this is one of them.
If none of the easy stuff works I will be putting the Jeep in more capable hands for scrutiny as I donât have much training as a mechanic. And yes, the jeep is parked in my front yard at 6700 feet. There are lots of boon docking and dirt bike opportunities around.
Itâs possible the tires and additional weight have something to do with the problem but I have had several jeeps in the past and none have ever developed this problem. Even this one only has the problem at over 70mph. Most of my jeeps in the past needed a strong tail wind to get to 70! 
Have you tried going uphill in a lower gear - D3 not D4, or whatever options your tranny offers?
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Just curiousâŠwhy is re-gearing a bad idea?
I have not. Going uphill at 80mph is turning about 27 to 2800 rpm. (Best I can remember)
I had to drive across much of Nebraska with the radiator cap loosened due to a leak that would spew fluid while under pressure, until I found a town with an auto parts store. It never boiled over
Your Wrangler must have been older and did not have a normal operating temperature of 195-220 F.
The larger tires create more drag but this is anticipated in the design of the vehicle as larger tires are a common modification.
The larger tires combined with the large bumper that disturbs the air flow to the grill is going to be a burden on the cooling system at 80 MPH on a mountain grade.
Internet says coolant boiling point is 226 degrees not under pressure.
The temperature of the coolant that is in contact with the cylinder head is hotter that that.
That sounds like it is geared correctly.
Your stock radiator should adequate. But it might be gunked up. I would think you would be experiencing overheating at lower speeds.
If all other system are operating correctly you **might need a larger aftermarket ** radiator.
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Have you verified air is getting thru the radiator? Take an air hose and blow through backwards and then forwards and see how much junk comes out.
are the radiator fins in decent shape? or are they all dinged up from rocks and road debris? (unlikely on a 2015, but itâs good to check, and free to look at.)
With the gearing much too high, and with the long steep hills, and with going 80 mph, I imagine that the accelerator is pretty close to being floored for a long period of time. The engine has far more heat to get rid of. Finally, I donât think the OP has defined what âoverheatingâ means. Is it boiling over, or is the temp gauge just higher than usual.
The temp gauge gets very close to the red and the engine reduces power. At that point I let off the accelerator. Once the ground flattens out again the temp cools back down rapidly.
A bad idea until you check out several issues more directly related to coolant temperature. Always look at the obvious things first, and the least expensive obvious things very first. @FoDaddy provided useful information about your tires and gearing, an education for me. The education is one of the big reasons I come here.