Tire Pressure Indicator and Gas Mileage

[2015Pumpkin]

Hey everybody...
2015 Mustang with the 3.7 V6...bone stock. Question about tire pressure is: does anybody else have a discrepancy between actual tire pressure and what the dash says? My dash indicates my tires are between 32 and 38 pounds of pressure but Ive purposely put 40 pds just to see what the dash would say. Come oil change time at the dealership is this something that can be 'reflashed' or reset?
Also...how far off is the mpg on the dash indicator to real life? Ive come REAL close to 32 mpg which I consider DAMN GOOD for a Mustang!! So is that ACTUALLY what Im getting?
Thanks in advance!!

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[Vlad Soare]

Most people would tell you that tire pressure sensors are notoriously inaccurate, though my experience is different. All four of mine agree perfectly with my digital gauge, and the ones I had in my previous car, a Mondeo, used to agree too.
Is the deviation the same in all four wheels? I mean, if you inflate all four wheels to the same pressure on your gauge, do all four sensors show the same value (albeit different from the gauge)? If you put 40 psi in all wheels, and a sensor shows 38 and another 32, then one of the sensors is faulty. But if you put 40 in all wheels, and all sensors show, say, 38, then I would suspect that your gauge is out of calibration.

The mpg indicator seems to me to be a bit on the optimistic side. Not only in the Mustang, but in all the Fords I've owned so far.

 

[Farkel]

https://www.mustang6g.com/forums/threads/how-to-adjust-your-indicated-average-fuel-economy.48903/

 

[MikeHTally]

The manual says not to use the TPMS as a tire gauge, so does the Ford app. I have a compressor and a reasonably-accurate tire gauge. They get regular usage as the temperatures change. Last Sunday, I adjusted the pressure in sixteen tires.. While I'm on the subject - check the air in the spare. We're about to start a 3,800 mile road trip. I aired up the wife's RAV, including the spare (it was down to 48#). Not good to have a flat and nothing to put on in its place.

The computer's fantasy about fuel economy is reasonably well-known. All my vehicles have been overly-optimistic about fuel usage. Every car I've had in the past was off, one by 14%. You can adjust most of the error out by going into the admin part of the computer. You'll find a setting with a default of "1,000". Back it down 20 points and calculate a few tanks of usage. If the computer is still off, adjust it again.

The "Fuelly" site allows you to track mileage, if you're serious about that. I've tracked my rides a long time using it.

 

[Cobra Jet]

Also best practice for checking tire psi is when the tires are stone cold before any driving.

 

[MikeHTally]

Another thing: If it's going to be on the interstate for a long time, add a few pounds to the pressure. A few hundred Explorer owners had to learn that one the hard way. The RAV will have an extra 4# in the tires when we start out tomorrow.

 

[Rapid Red]

MPG ............. don't care never have never will. I buy a car to drive, not piss & moan about cost .

For tire pressures, use the Ford Pass to monitor things. Tires are balanced as needed, before I take it out .

Looking over the app whenever & seeing a tire low, 1 psi. Check 4 and set if required.

TPS as near a I can tell do exactly and work as they should. I would suggest if someone it having problems. Pressure gauge & actual pressure readings. Consider (horrid thought) purchasing a different or better pressure gauge ....

 

[Bikeman315]

Another thing: If it's going to be on the interstate for a long time, add a few pounds to the pressure. A few hundred Explorer owners had to learn that one the hard way. The RAV will have an extra 4# in the tires when we start out tomorrow.

Sorry Mike, that is not good advise. My wife owned a 1998 Explorer that had Firestone tires. We had them replaced with no problems. That said overinflation is overinflation regardless if on the highway or a back road. A tire will gain 3/4 psi at highway speed so at the factory recommended 33 psi I will be running approx. 36/37 psi on the highway. Of course the good news is you will get slightly better fuel economy.

The Ford/Firestone issue was farce. Each blamed the other. But many accidents were found to be caused by under inflated tires (not properly inflated tires), creating extreme heat that damaged the bead. Once the tire let go the high center of gravity and "other" issues caused many Explorer drivers to lose control and flip their vehicles.

 

[TXGTPig]

So a pretty accurate way to figure out your actual MPG. When you pull in to the gas station note how many miles you got on that tank. Then after you fill up take that number and divided it by the amount of gallons you just put in your tank. I.E. you traveled 227 miles, then topped off with 13.589 gallons. 227/13.589 = 16.704MPG.

 

[MikeHTally]

Sorry Mike, that is not good advise. My wife owned a 1998 Explorer that had Firestone tires. We had them replaced with no problems. That said overinflation is overinflation regardless if on the highway or a back road. A tire will gain 3/4 psi at highway speed so at the factory recommended 33 psi I will be running approx. 36/37 psi on the highway. Of course the good news is you will get slightly better fuel economy.

The Ford/Firestone issue was farce. Each blamed the other. But many accidents were found to be caused by under inflated tires (not properly inflated tires), creating extreme heat that damaged the bead. Once the tire let go the high center of gravity and "other" issues caused many Explorer drivers to lose control and flip their vehicles.

Lots of tire manufacturers disgree.

Sorry Mike, that is not good advise. My wife owned a 1998 Explorer that had Firestone tires. We had them replaced with no problems. That said overinflation is overinflation regardless if on the highway or a back road. A tire will gain 3/4 psi at highway speed so at the factory recommended 33 psi I will be running approx. 36/37 psi on the highway. Of course the good news is you will get slightly better fuel economy.

The Ford/Firestone issue was farce. Each blamed the other. But many accidents were found to be caused by under inflated tires (not properly inflated tires), creating extreme heat that damaged the bead. Once the tire let go the high center of gravity and "other" issues caused many Explorer drivers to lose control and flip their vehicles.

Sorry, I've seen with my very own OEM peepers that the pressure goes up more starting with the placard number than by adding 3-4 #.

 

[melwff]

Hey everybody...
2015 Mustang with the 3.7 V6...bone stock. Question about tire pressure is: does anybody else have a discrepancy between actual tire pressure and what the dash says? My dash indicates my tires are between 32 and 38 pounds of pressure but Ive purposely put 40 pds just to see what the dash would say. Come oil change time at the dealership is this something that can be 'reflashed' or reset?
Also...how far off is the mpg on the dash indicator to real life? Ive come REAL close to 32 mpg which I consider DAMN GOOD for a Mustang!! So is that ACTUALLY what Im getting?
Thanks in advance!!

What do you mean "supposedly" you inflated them to 40 psi?
Did you use a reliable handheld digital or analog tire pressure gauge?
Why did you set them to such a high pressure?
If you have the original TPMS sensors they are 6 years old and are entering the end of life window for their batteries.

 

[2015Pumpkin]

Most people would tell you that tire pressure sensors are notoriously inaccurate, though my experience is different. All four of mine agree perfectly with my digital gauge, and the ones I had in my previous car, a Mondeo, used to agree too.
Is the deviation the same in all four wheels? I mean, if you inflate all four wheels to the same pressure on your gauge, do all four sensors show the same value (albeit different from the gauge)? If you put 40 psi in all wheels, and a sensor shows 38 and another 32, then one of the sensors is faulty. But if you put 40 in all wheels, and all sensors show, say, 38, then I would suspect that your gauge is out of calibration.

The mpg indicator seems to me to be a bit on the optimistic side. Not only in the Mustang, but in all the Fords I've owned so far.

Hey Vlad...first of all I inflated all 4 tires to what the gas station air pump said was 40 and also indicated on my SLIME air pressure gauge. THEN today I used a cheap old tire gauge and it showed closer to what the car TP indicated on the dash. SO now I am really confused!! LOL...

 

[2015Pumpkin]

The manual says not to use the TPMS as a tire gauge, so does the Ford app. I have a compressor and a reasonably-accurate tire gauge. They get regular usage as the temperatures change. Last Sunday, I adjusted the pressure in sixteen tires.. While I'm on the subject - check the air in the spare. We're about to start a 3,800 mile road trip. I aired up the wife's RAV, including the spare (it was down to 48#). Not good to have a flat and nothing to put on in its place.

The computer's fantasy about fuel economy is reasonably well-known. All my vehicles have been overly-optimistic about fuel usage. Every car I've had in the past was off, one by 14%. You can adjust most of the error out by going into the admin part of the computer. You'll find a setting with a default of "1,000". Back it down 20 points and calculate a few tanks of usage. If the computer is still off, adjust it again.

The "Fuelly" site allows you to track mileage, if you're serious about that. I've tracked my rides a long time using it.

Welllll...first I have to ACQUIRE a spare!!! LOL...but I will also try that reset in the admin. Thanks!

 

[melwff]

Hey Vlad...first of all I inflated all 4 tires to what the gas station air pump said was 40 and also indicated on my SLIME air pressure gauge. THEN today I used a cheap old tire gauge and it showed closer to what the car TP indicated on the dash. SO now I am really confused!! LOL...

To start with gas station air pumps are notoriously inaccurate.
Tire pressure should be checked and adjusted on a completely cold tire.
Why would you set your pressure to 40 instead of what the label on the drivers door post lists?

 

[2015Pumpkin]

https://www.mustang6g.com/forums/threads/how-to-adjust-your-indicated-average-fuel-economy.48903/

THANKS

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