Jeep and FCA (Stellantis) have got their nuts in a vise on this one. The techs I've spoken with want to fix it but can't and have work (and money) sitting in a parking lot collecting dust. Owners are paying for vehicles they cannot drive and cannot get fixed which adds to frustration and brand...
To prime it, listen for the audible change in pitch on the lift pump and you're set. Do it a few more times if you wish but once the tone changes the pump is primed.
Technology issues aside, no manufacturer is going to give you the secret sauce to throw their product into limp mode. This would be a lemon law lawyers dream come true.
If you want a true test, you need a control. Take the grill off and run a 10 mile circuit - city and highway at varying speeds. Record the high and low temps.
Install the old grill and run the same circuit. Record high and low temps.
Install the new grill and run the same circuit. Record...
My load range C Falken A/T3W 33's are 10.5" wide. Anything wider would begin to negatively affect fuel economy as those would be heavy tires. Granted, these weigh in at 64 pounds each but 35's are 70 pounds plus.
You’ve got a few options.
The best option in my opinion is to get them sanded down, remove any rust and have the powder coat refinished.
A cheaper option is to sand, prime and paint. The finish won’t be the same as when they were new but it will stop the rust from spreading.
The only piece that can break easily is the trim piece covering the rear window defrost wiring that connects to the driver side near the rear door.
Be careful when removing it and you'll be fine.