Anyone else notice significant fuel economy improvement after break in?

[waveslayer]

I just got back from a trip and got to once again test Lucilles distance running. rain was prevalent for a bunch of the trip and when things cleared I got a chance to run I-64 in identical conditions minus the rain, possibly barometric pressure, but temps were equal. The only difference being before I ran the defroster pretty much constantly, after I had a little bit more... cargo... and I didn’t run the defroster. I gained almost a solid 1mpg on just not using the defroster / a/c. I got ~16.5 on the before, ~17.25 on the return, same stretch, 70-75mph indicated (mostly the 75).

I never noticed any sudden improvement or degradation the truck’s been consistently since day one.

What octane are you running ?

My wife thinks I only have 3 guns

 

[rtmozingo]

Mine didn't improve appreciably after the first thousand miles. It is definitely sensitive to fuel octane and tire pressure though. 89 or 91 gets worse fuel economy than 93, and I've also lost about 1.5 mpg from lowering the rear tire pressure. Down at 30 because it's comfy but for the next long trip I'm airing them all back up to 42.

Why would you run 42? 38 is recommended and is still too much. Got overinflated wear in 10k miles at 38.

 

[Blusmbl]

Why would you run 42? 38 is recommended and is still too much. Got overinflated wear in 10k miles at 38.

Fuel economy! Only for highway trips. The side of the tire says cold pressure of 45 psi if I remember right, compared to the door sticker of 38.

 

[squeak]

Fuel economy! Only for highway trips. The side of the tire says cold pressure of 45 psi if I remember right, compared to the door sticker of 38.

Supposed to go with the door sticker because it's based on the vehicle.

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[Blusmbl]

You can run any pressure in the tire between the value listed on the sticker and the maximum listed on the sidewall. Running lower than the door sticker reduces towing capability. There is no harm in inflating above the door sticker value besides potentially wearing the center of the tire out faster and a bouncier ride, but I'm willing to make that tradeoff for better fuel economy if I'm driving a few hours away.

 

[gregaf3]

I got 15.4 once...

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[goblues38]

Fuel economy! Only for highway trips. The side of the tire says cold pressure of 45 psi if I remember right, compared to the door sticker of 38.

Always go by door sticker. Tire is made for many, many makes and models. Manufacturer takes that tire and designs a specific set up for that tire. The door sticker is what they engineered the tires to work with that set up.

No way inflating to 45 saves you enough gas money in extra MPG to outweigh the cost of worn out tires 5,000 miles too early.

Plus, suspension geometry is off with over inflated tires. smaller contact patch. in an emergency situation, you could lose control when normally you would not.

agree. to each his own. not trying to be preachy.....ALWAYS...door sticker.

 

[smurfslayer]

What octane are you running ?

My wife thinks I only have 3 guns

I ran 87 for both runs.

 

[jzweedyk]

Always go by door sticker. Tire is made for many, many makes and models. Manufacturer takes that tire and designs a specific set up for that tire. The door sticker is what they engineered the tires to work with that set up.

No way inflating to 45 saves you enough gas money in extra MPG to outweigh the cost of worn out tires 5,000 miles too early.

Plus, suspension geometry is off with over inflated tires. smaller contact patch. in an emergency situation, you could lose control when normally you would not.

agree. to each his own. not trying to be preachy.....ALWAYS...door sticker.

I agree, 100%. Radials are not like bias ply tires, pressure does not influence mpg nearly as much.

 

[Blusmbl]

Always go by door sticker. Tire is made for many, many makes and models. Manufacturer takes that tire and designs a specific set up for that tire. The door sticker is what they engineered the tires to work with that set up.

For most of the dedicated performance products (not just Ford, same applies for GM, Chrysler, etc) the OEM tire is designed specifically for the vehicle. The C load range version of the 315/70/17 A/T KO2 is made just for our trucks. If you go to Tire Rack and type in that tire size, it even comes up as "Ford" and the only vehicle this tire has ever been used on in an OEM application is the Raptor. The E range tire is much more common.

I'm not going to argue AT ALL that 38 is optimal based on the door sticker, but if they weren't safe at 45 it wouldn't be on the side of the tire for a tire made exactly for the truck.