I read through this thread and several builds trying to understand what was marketing hype (BS?) and what was more real world expectation. My take: Yes you might fit 37s with no lift (I mean we know it can be done with 38s and no hi-line

) but wouldn’t be functional in way most of us want to use our Jeeps. To really see gains you need to go up and back meaning highline. It will be lot of work fitting everything back under the hood.
With above in mind here are my thoughts after looking at 4 potential options, sorry if some of this is repetitive but do like getting input before spend what will be significant $ after match it with rear armor, sliders etc.
PS and TnT are basically blowing smoke up consumers ass with tire size claims.
GenRight makes no specific tire size claims and is pretty blunt with how much work is involved. They also come as most expensive as things like inner fender, relocation brackets, turn signal provisions, etc. are all purchased separately. They are listed at 6 lbs/fender for 0 flare which is awesome but doesn’t include inner fender etc.
Nemesis tire size claims seem reasonable but is harder to find real world examples. An fully complete kit for $999 is appealing (flare is $350). Shipped weight is 50 lbs. They probably undersell amount of work associated with install and avoid fact that will require cutting by suggesting a hood that is no longer available.
PS: Steel or Aluminum. ”2½" further back compared to typical tube fenders, and about 4" further back than the stock Jeep flares. But the wheel opening on the XC's is
3" higher than standard DeFenders, providing
Massive Tire Clearance with minimal lift! While there are specific considerations to address with any particular Jeep, in most cases you should be able to run 37" tires with no suspension lift, and
40's with just couple inches of lift!”
TnT: Steel. ”Do 40 inch MT/Rs with only 4 inch of lift interest you? TNT Full Replacement HyLine tube fenders added to your 97-06 Jeep Wrangler TJ/LJ will significantly improve your Jeep's abilities on and off road. By enlarging the wheel opening to the extent that we have, you have the potential to run as large as a 37 inch tire on a stock suspension”
GenRight: Steel or Aluminum. steel-“constructed to sit 3-3/4" higher that stock to allow you to run bigger tires with minimal lift” aluminum- “Hi-Fender model opens the wheel opening 3" up and 3" back“ “Installing Hi-Fenders is a lot of work! You have got to really want these fenders on your Jeep! It is going to take a lot of time to install them! If you are not up to the job, have a professional install them or DO NOT buy them!”
Nemesis: Aluminum. “Whether your aim is a 35 inch tire with minimal lift or you are going all the way with 37 or even 40 inch tires with a more in depth suspension build, the added 4 inches on top of the tire and 5 inches of clearance behind the tire” “designed to work with the AEV highhood” “Installation can be handled by the average home installer, and can be completed in a day for the kit, using basic hand tools. There is no drilling or cutting required to install these fenders, you will reuse all of your factory hardware”