I know what you're thinking - "why the fuss? Aren't the two inexorably associated for aggressive tires like the KO2?" But what about tires that aren't quite as extraneously bulky? Stock tires for lower trims especially are GY Fortitude HTs. P265/70R17 usually weighs around 38 lb for this tire.

Now, 285/70R17 (~32.8") looks really attractive to me, not for the sake of gaining ground clearance, but to better fill what I think are hideously "empty" wheel wells on the F150. I don't wheel hard, so P-rated is just fine. Some AT capability is important, but all-weather performance is of more value to me; thus, my first choices would be along the lines of Cooper X/T4 and Yoko G015, both available in 285/70 (Cooper's official website doesn't show it, but they do exist). The lesser weight is also more attractive to me. The Falken Wildpeak AT3Ws have been good to me so far, but I haven't had any chance to test their mettle in serious winter conditions, and they are heavy.

285/70R17 for the P-rated X/T4 and G015 weigh roughly 43-44 lb

265/70R17 for the P-rated Wildpeak weighs roughly 45 lb
265/70R17 for the E-rated Wildpeak weighs roughly 52 lb

Now, casting aside durability concerns, how differently would a 5.0 3.73 truck handle these tires? Aside from the speedometer that can be fixed via Forscan or Hypertech programmer, which is more difficult to turn for the powertrain (and therefore a difference more noticeable in driving), the lighter & larger tires, or the smaller but heavier tires?

 

IIRC for every pound added to the tire weight will feel like 7 lbs of additional mass to the vehicle's weight. Example a tire weighs 5 lbs heavier than the previous tire will be like adding an additional 140 lbs to the vehicle (5x4)x7=140. Probably won't notice any difference as long the tire diameter stays the same.

 

Adding 1" to tire diameter with 3.73 gears will very likely not be noticeable. I have 275/60R20 (33") on mine, with the 2.7L and 3.55 gears, and can't tell a difference in ride, handling, or acceleration compared to the stock 275/65R18 combo.

 

 

Tire weight comes into play during acceleration and brake events. At constant speed it should be near neutral. At constant speed the tire's rolling resistant and tread pattern plays a bigger roll in the fuel economy.

Can't really compare the GY Fortitude HT to anything else since it's designed to be a extremely light highway tread tire for manufacturers to fuel economy goals.

Curious what is your fuel economy comparing the OEM GY vs. Duratrac vs. Wildpeak?

 

P-rated Pirelli Scorpion All Terrain Plus.

No idea on MPGs. I don't track it. My guess would be little to no difference. I don't fill up any more frequently than I did before.

Driving a 5.0 with 3.73s, you're already getting the worst economy possible in the F150.

Didn't make any Forscan changes.

 

Yup. Basically no tire save for other highway tires will come close to the Fortitude's weight. But it sounds like there are no deal-breaking ramifications upsizing to 285/70R17, so the X/T4 or G015's 43-44lb 285/70R17 are probably the route I'll take eventually.

I can't compare the Duratrac to Wildpeak, but I can compare the Fortitude (P265/70R17, about 17-19MPG) to the Duratrac (265/70R17E, about 13-15MPG), and the Fortitude (P265/70R16, about 19MPG) to the Wildpeak (P265/75R16, about 17MPG).

@tenx82 I'm not after the 5.0 for the best mileage, but the "worst" is pretty subjective. I averaged 18MPG with heavy city emphasis with the stock tires on the Gen2 Coyote 3.73; it had enough oomph for me to get around effortlessly without digging further into the pedal. From what I gather, 3.5EB is no better, and once you drive fast enough/hard enough even the 2.7EB starts spooling up the turbos and MPGs go down the drain. But back on track, that's the reason I probably won't consider LT tires ever again. I'll probably just upsize with the light AT tires, similar to what you're doing with your truck. But you do have an advantage in that you only went from 32.1" to 33", for me the jump is 31.6" to 32.8".

 

I would also look into aftermarket rims, as they are usually lighter then oem. I just went from the stock goodyear 275/65/18 which are 48lbs to nitto ridge grapplers 285/70/18 which are 60lbs but I did go with moto metal rims that were 27lbs opposed to the oem which are 32lbs so that saved some weight. My truck is a hdpp eco with 3.73's and I didn't really notice a difference.

 

That's a good suggestion, I'll keep that in mind. I reckon if I actually run the Fortitude HTs until the bottom of the sipes (not full-depth), I can probably afford to swap the wheels and tires at the same time. The AR931 looks good but is obscure and no one has detailed specs on the weight and whatnot.

I think the stock 275/65R18s are about 39lb, so the Ridge Grapplers are quite a bit heavier. Speaking of which, I emailed Cooper about the weight of 285/70R17 X/T4s and the official spec is 45lb, which is not bad. Good to have some official data.

 

I thought I had researched everything, looking at the differences from 6-8-10 ply and tire height, weight and tread pattern. On my last truck, a 2011 GMC with a 5.3 and mild tune, I started with:
Cooper Zeons in a 275-60-20 33.03 tall 47 lbs 16-17.5 mpg avg 6 ply
Nitto Trail Grapplers 295-55-20 32.91 tall 70.02 lbs 16-16.5 mpg avg, 10 ply, then finally
Goodyear Duratracs 295-60-20 33.00 tall 46 lbs 13-14.5 mpg avg.6 ply
Now looking at the specs, the Goodyears should have yielded the best weight to MPG average, but they were the worst.
You also have to look at tire compound and tread pattern. Even though the Nittos were 20-30 lbs heavier, they delivered the best weight to MPG avg for me.
Just some more useless figures to ponder.