I feel 35 is low as well. Just from a handling standpoint. Unless I come off the mountain to travel, I do not drive on a straight road. Even with the 20s it feels a little mushy in the curves. I think 38 to 40 would improve the handling greatly. Not sure what it would do to the ride but I will try to see. I am not sure how I feel about the hancooks, I've never purchased that brand. I hardly have any use to determine (1,000 miles) but I can tell you that I will not be putting hancooks back on it.
That's the key. When Ford "recommends" a tire pressure, they are also heavily concerned with perceived ride quality/harshness, as they don't want people complaining that their SUV rides like, well, and SUV. The general motoring public is stupid. They don't understand how vehicles work. If they think that their new "car" should ride like the Civic they traded in, then there is no convincing them otherwise. So, Ford, and other manufacturers have to very cognizant of "NVH". Spec-ing a lower tire pressure makes for a "softer" ride, reducing customer complaints, and garnering better reviews in the press (also often pretty ignorant of how cars work) They figure that the typical "soccer-mom" consumer of this vehicle will likely not notice, or be able to recognize, the handling effects from small reductions in tire pressure. They are also not likely to "connect-the-dots" when their tires eventually wear out on the outside edges while still having tread in the middle. They'll just accept that the mechanic says they need new tires. They will, however, scream bloody murder to the dealer and everybody else who will listen when their new "car" ( which isn't a car) has a slightly rough ride over rough roads.
This scenario is exactly how the whole roll-over/Firestone tread separation thing came about. Ford initially (well, for years really) recommended a ridiculously low tire pressure, in order to meet marketing department requirements (not engineering) regarding ride quality. In any case, the factory recommendation is really only even remotely somewhat valid when the vehicle has all the oem parts/configuration, including the EXACT oem tires (including identical replacements of course). Once you change anything about the tires, such as size, tread pattern or compound, speed rating,etc...., then you probably need to reevaluate the appropriate tire pressure for your unique situation.
There are (2) ways to determine proper tire pressure:
Immediately after driving for a distance representative of a typical trip, measure the temperature of each tire, in 3 different locations across the tread. an outer tread "block", a tread block across from that in the center of the tire, and the inner block. If the middle is more then a couple degrees hotter then either inner or outer block temps, then the tire has too much pressure, and you should air it down by 1 or 2psi, and repeat the test after allowing the tire to completely cool first. If the middle is more then a deg. or 2 cooler then the outside temps, then the middle of the tread is not making sufficient contact with the road, and that tire needs more air. Go up 1 or 2psi, and repeat the test
Also, you can use the inner/outer tread block temps to determine if your alignment is right; well camber at least. If the outer block is hotter than the inner, the tire is "tipped" out (This will wear the outside of the tire faster), and you need to increase your NEGATIVE camber (ie, if you are at, say, -0.10 camber, then maybe try having it set to -0.25) The greater the temp difference, the bigger the change you will need to make. Conversely, if the inner tread is hotter, you have too much negative camber (This will wear the inside of the tire), and need to go slightly more positive. (Ie, you have -0.70, try reducing it to -0.40)
These temps can be measured with either a contact-type probe pyrometer,or a non-contact infrared pyrometer. The infrared type is readily available in many auto parts stores. The probe type can be purchased from a number of places that cater to circle track racers. A decent cheap one can be had for around $50. Summit or Jegs may sell them. You can try your local speed shop, online vendors such as Day Motorsports in Texas or Behrents in NY
Another way to gauge proper tire pressure over the long term is to monitor wear patterns. If find the tire is noticeably more worn on the edges, than in the middle, then your tire pressure is too low, period. Doesn't matter what the sticker says, or Ford, or your cousin,etc... It's simple physics (ok, maybe not that simple.) An underinflated tire "collapses" in the middle under the weight of the vehicle. This prevents the center of the tread from making full contact with the road and carrying its fair share. It forces the in/out side of the tire to carry the extra weight/traction, and reduces traction/hadling and prematurely wears out the tire.
An overinflated tire will "bulge" in the middle, and wear the center of the tread more.
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=1
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=3
Also, with winter approaching, remember to check and reset your tire pressures when the outside temperature changes. For example, last week we still had 78deg+ days. The tires on my car were set at 36psi. The temperature dropped into the high 50's, and when I rechecked, the pressure were uniformly down about 4-5psi, making for underinflated tires.
