eye.surgeon

What's your ride like with those E rated tires when not towing? I had heavy load tires on a previous 2500HD and they rode pretty rough unloaded. I'm sure that's why Ford doesn't include them in the Max Tow package, although they probably should be. It would be bad for the test drive.

Wiggum

LOL @ this thread ...

Guy 1: "Hey, wanna know how to get better MPG when towing?"
Guy 2: "Sure, educate me!"
Guy 1: "Tow something a LOT lighter and a LOT more aerodynamic."
Guy 2: (facepalm)

Adobe2X

I hesitate to say, as those keyboard ninjas are going to say that I am being idiotically obvious........but yes, the impact harshness unloaded is quite noticeable.
For those in the know, the trade off when towing would be worth it, but yes, i agree with you that the initial test drive might be off putting with these tires.

Wiggum

E rated tires on an unloaded F150 does make for a stiff ride ... but I've found that keeping my tires at 50psi makes the ride just fine. Stiffer than normal, but not jolting. Pump them up to 60-65psi and you'll get beat to death.

I dont notice any more "sag" in my tires when at 50psi than I did when at 60psi ... I bet I could drop it to about 46psi and still be fine (no uneven wear). It MIGHT net me a little less gas mileage by a fraction ... but ride comfort is greatly increased by lowering the pressure.

Adobe2X

OK.......last time.....had I known that using only 65% or so of the max tow rating was going to affect my pocketbook so severely, I might have made better choices initially in my choice of TT.
I can see getting cruddy mpg if you tow 11,300 pounds....but for those out there considering towing only 8,800 pounds OR finding a TT weighing less and getting THAT much better mpg --- I still think that my information might be useful to them.
If you only tow once or twice a year for a couple of 100 miles, then this information is no big deal and you should feel free to load up your TT with all of the options and weight that you want or need. For me, this is going to affect us positively in the realm of 1,000's of dollars in gas money.
I don't have to defend myself for trying to help others here, and I have the history and the "thanks" to prove it.......

Wiggum

dude ... relax. I'm just playing around. Not poking fun at you per say. I do stuff like that all the time, where I say or explain something and it makes sense to me, but it comes out wrong and/or the perception of it to others is something completely different.

Yes, your E rated tires do make a difference, especially when properly inflated. But everything else with your towing does come down to a simple equation: How much harder is your engine having to work to tow whatever it is you're pulling. The factors that directly affect that are weight of what's being towed, and aerodynamics.

Think about this ... People lift their trucks up about 3-4" and put heavier bigger tires on the truck, and they all report loss of about 1-2MPG just from that. Of course adding almost 9,000 lbs of non-aerodynamic load to your truck is going to really affect MPG.

anyway, you sound like you're good to go now w/ the "better" Trailer you're towing ... so it's all cool.

king nothing

Did the tires cost you any mileage when unloaded? Thinking about going to e rated tires on mine. Like others I can't believe they didn't come standard on the max-tow trucks. I probably only put a thousand miles towing a year but I'd feel better with better tires

Wiggum

I'm running 275/65r20 E rated tires on my FX4 ... tires are 34" instead of the stock 32" ... and quite frankly, I barely see any drop in my MPG.

HCFX2013

That's probably because you haven't calibrated your speedo to compensate for the tires yet. Same thing happened on my '11, then I calibrated the speedometer and almost shat myself. I just stopped looking at MPG and enjoyed the awesome look and stance the tires offered. I plan to apply the same method when I upsize on my '13.

That said, I've never understood complaints about MPG while towing..(Not saying your thread here isn't informative, Sterlingone) as most of the time you're pulling a load that accounts for about the same weight as your truck itself.

With that logic, If your engine is pulling double the weight, wouldn't that mean you'll get half the MPG? Pretty primitive theory, but there could be some truth to it. So if you average, say, 17mpg unloaded, 8.5mpg towing 5500lbs sounds about right.

Wiggum

Actually, when going to bigger tires, your speedo will show lower speeds than you're actually going, and your odometer will show less miles than you've actually traveled. This is because both of those gauges read off axle revolutions ...

Case in point: the 31.9" stock tires have a circumference of 100.166" (31.9" x 3.14). Divide that by 12 to convert inches to feet and you get 8.347'. That's how far you travel with each revolution of that tire. Divide 5,280 feet (1 mile) by 8.347' and you get 632.56 revolutions per mile on THAT tire. That means you need 632.56 revolutions per mile using the stock tires. So every 632.56 revolutions your odometer turns over 1 mile.

When you switch to 34" tires (mine are actually 34.2") ... you do the same math, and come up with 590.01 revolutions per mile. So, every mile that my truck THINKS I'm going, I've actually gone 1.07 miles. So, if you are still tracking here, that means my truck THINKS I'm getting WORSE gas mileage than I really am, because i'm using more gas to travel less miles (according to my gauges).

Once calibrated for accuracy, you SHOULD see your MPG average increase ... not decrease.

When I do the manual math on it ... I take what I see now, which is an avg of about 13.6mpg ... multiply that by 1.07 ... and I get a TRUE average MPG of 14.552. That's simply because my truck THINKS I've only gone 13.6mpg ... when in fact I've traveled 1.07 times that distance on that same gallon of gas.

Going to smaller tires will cause your speedometer to read higher than you're actually traveling, and your odometer will turn over miles more quickly than it should. It's the opposite effect of going to larger tires.

That said, the NAV system in the truck doesn't tie into the axel revolutions. It is smart enough to use the GPS to locate you. So, regardless of tire size and other gauge readings, it will show you accurately where you are, and when to turn.