I was going by published specs. What the factory eventually uses may vary. But according to published specs, the TH gets tires that are shorter. I believe the Limited was listed as using a 215/65-18.
Published specs is "225 / 55R18 All Season Tires" for limited and "215 / 65R17 All Terrain Tire" for trailhawk. So tehnighthawk is correct, TH tires are the largest diameter.
So, what exactly can Trailhawk do that non-Trailhawk models would absolutely not be unable to do?
And:
How does Trailhawk stack up to the off-roading essentials listed?
http://jalopnik.com/this-is-what-makes-a-vehicle-unstoppable-off-road-512501606
TRailhawk models get a better approach and departure angles due to different bumpers. It gets tow hooks so you cna make use of come alongs or a tow if needed. It has about an inch of lift, and as noted above, minusculely larger tires with a mildly more aggressive tread pattern. and a 20:1 crawl ratio available.
I'll go throught he jalopnik points as best I can:
1) ground clearance - 4x4 renegades are about typical for soft roading SUVs and CUVs these days. 7 and a bit inches. The TH is a bit over 8 inches. It's still not spectacular, but it's not bad. I had an 85 ram charger with 35x12.5" tires on it a long time ago. Once you measured to the diffs, barakes, and steering linkage, I only had about 10" of clearance. If I wanted more I had to navigate obstacles through the maze of my undercarriage. You can do a lot (a lot easier too) with a 4 wheel independent suspension setup that has a big clear swath down the middle.
2) skid plates - TH has some, it looks reasonably well protected, but I wouldn't want to drag the entire vehicle's weight on one.
3) approach departure and breakover angle. It has more departure angle than wrangler (2 door), about the same breakover, and about 10 degrees less approach. It's slightly less capable than the wrangler, but IMO it's a better set of angles. With the wrangler, you can drive up things you can't drive back down without catching the rear bumper, and I've seen that happen.
4)wheel articulation. the TH has more than the other versions, at least in the rear. It's something like 8 inches. It certainly not the best production stat, and there's always lots of very particular language surrounding that 8 inch number, so who knows. It is better than the lattitude, limtied and sprot though.
5) low end torque. Dunno, we need a dyno chart. Certainly the diesel versions will be well supplied here, but the 2.4? The 2.4 should be better than the 1.4 though. even if the 1.4 has good torque, a tubro means you don't get it until you rev up more, and fro off-road crawling, you want near electric motor behavior of lots of ttorque early.
6) gearing. the TH gets a 20:1 crawl ratio the other trims don't. It's certainly better than nothing, but hardly knocking anyone's socks off compared to things with a 2 speed transfer case.
7) tires. TH gets slightly better than other trims. It remains to be seen what can be slapped on the thing if kept stock other than wheels and tires, but in the factory dimensions, there is very little to choose from that are AT or MT tires.
8) locking diffs. Like jalopnik notes after the bold, there are lots of ways to do this. renegade does this, and not just the TH.
9) high mounted air intake- most cars these days use some form of cowl induction to get fresh cool air in. That's great, but they are implicitly assuming that like old school carburated vehicles with simple wire looms, your electric is mostly up high. That's a stupid assumption these days. The renegade gets you 19" of protection for those bits. They are over simplifying ability to ford water, so I'd kind of disregard this one as being meaningly informative.
10) robustness - they are using this a sort of a generic catch all for a bunch of things. regarding renegade, they get double wall control arms for the 4x4 models. Th gets skid plates. One non-obvious thing they don't really address here is that all those tough bits are relative to the mass of the vehicle. Compared to an old IHC scout, renegade is not light. Compared to most of what you can buy new today, it is.
11) visbility- renegade is probably not awesome with the rear pillars and a-pillars being what they are. On the other hand it has the backup camera, which can help.
12) light and small.. see above. It's relative. They are right that something like the samurai can be an insane off-roader.
13) tow points. TH has them, other trims don't. THe weight of the vehicle means that come alongs and such are going to be more effective than with something bigger and heavier.
14) a frame - this is old school thinking. I'm sorry, but you can build a unibody chassis that is stiff enough you can destroy the equipment used to measure such by ripping the reinforcements out of their reinforced concrete foundation. Body on frame is simpler to screw around with though. Where does the TH stand on teh spectrum of surviving off-road? Who knows. Only time will tell if jeep built something tougher than the top 20% of abusive customers.
And I'll add 15) The nut behind the wheel. Driver technique trumps most everything. The story of top gear's oliver is a good example. I also saw a broadcast of a mud festival where they had the national guard in attendance with some big bad 6 or 8 wheel vehicle to make sure anyone stuck could be gotten out and the fun could continue. It got stuck along with several other custom lifted off-rad vehicles that cost many tens of thousands. Some dude who knew what he was doing in a barely modified samurai kept driving aorund them the whole time.