Tire Pressure Indicator and Gas Mileage

[ORRadtech]

Very true. Sometimes you might fill the tank till it almost runs out and the next you might cheat yourself by a gallon or a half. Good point!!

If you're filling your tank until it almost runs out then you're going to cause yourself problems with the car. You can and will damage the Evaporateive Purge Valve.
What Ford recommends is setting the auto shut-off on the gas pump handle and not topping off the tank once it shuts off. I always used to top off the tank because I felt like it never filled it up completely. I've since killed 2 EVPs and the dealer has told me topping the tank off is why.
I now fight the urge and mostly succeed.

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[2015Pumpkin]

If you're filling your tank until it almost runs out then you're going to cause yourself problems with the car. You can and will damage the Evaporateive Purge Valve.
What Ford recommends is setting the auto shut-off on the gas pump handle and not topping off the tank once it shuts off. I always used to top off the tank because I felt like it never filled it up completely. I've since killed 2 EVPs and the dealer has told me topping the tank off is why.
I now fight the urge and mostly succeed.

Thanks for that info!

 

[Garfy]

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.

It was NOT a tire issue on those early Explorers. Ford's sticker on the door jamb recommended 26 psi on the Wilderness A/T tires (which was a bad choice due to it having a Temperature rating of "C", the worst rating of A, B & C). Ford did this because the first generation Explorers had an issue where if inflated to 35 psi the vehicle would want to roll over on hard turns; deflating the tire to 26 psi greatly reduced this tendency. The proof that it wasn't a "tire issue" is the fact that the same year models of the Chevy S10 Blazers used the exact same size and model of tire WITHOUT any incidents of blow outs. Why the difference? The Blazer tires was factory recommended to have 35 psi. Both the Blazer and Explorers were similar in weight so that's not a variable. Later generations of the Explorer became wider, lower and heavier which allowed them to increase the tire pressure without having the tendency to roll over. Bottom line is if Ford wanted to run that low pressure for that heavy of a vehicle, they should have picked a tire that was Temperature rated "A". Then, the blow out problems wouldn't have occurred. To be fair, Firestone DID find one location that produced that size Wilderness A/T tires that used a different method of applying the adhesive to bond the tread to the carcass; they stopped production at that location. However, a lot of the tires that failed were not only from that location so it shows that the tire application was improper, not how the tires were made.

 

[Garfy]

If you're filling your tank until it almost runs out then you're going to cause yourself problems with the car. You can and will damage the Evaporateive Purge Valve.
What Ford recommends is setting the auto shut-off on the gas pump handle and not topping off the tank once it shuts off. I always used to top off the tank because I felt like it never filled it up completely. I've since killed 2 EVPs and the dealer has told me topping the tank off is why.
I now fight the urge and mostly succeed.

I guess you were fortunate it was just a purge valve issue. It could be worse by damaging the carbon canister which is much more expensive to buy and to install. Overfilling a tank can cause liquid fuel to enter into the canister which would require its replacement. There's a reason why fuel tanks have the space near the top that's empty and normally can't be filled, but if you keep pushing fuel into it the liquid fuel can make its way into the charcoal canister. I've seen it occur on a number of other cars so I'd stop once the nozzle clicks off.

 

[Garfy]

First of all...I DIDNT say I SUPPOSEDLY inflated them to 40... I said PURPOSELY inflated the tires to 40.
I used an analog gauge. I inflated them to 40 JUST to see if the TPMS would also indicate that tire pressure...which it didnt. Lastly...I did not know that TPMS's have batteries...SO...thanks for that info. I will have to remember that when I take it in for the first oil change and tire rotate at the shop! Thanks!

Most TPMS sensors have a battery life of approximately 10 years (lithium batteries). They're not serviceable so once one goes bad, replace all 4 sensors at the same time. Most TPMS tools will give you the status of the sensor battery as well. I'm not sure about Ford sensors but I've seen Honda OEM sensors last well over 10 years, though the more you drive the more the battery drains as it transmits a signal periodically while the tire is rotating. That being said, my Hondas had well over 110,000 miles yet the sensor were still good (I replaced all 4 since my daughter was moving to the mainland and I didn't want them to have to deal with the costs of replacing those sensors; here they charge over $110 each and I was able to buy all 4 new ones for $50 and my labor was free).

 

[Vlad Soare]

It was NOT a tire issue on those early Explorers. Ford's sticker on the door jamb recommended 26 psi on the Wilderness A/T tires (which was a bad choice due to it having a Temperature rating of "C", the worst rating of A, B & C). Ford did this because the first generation Explorers had an issue where if inflated to 35 psi the vehicle would want to roll over on hard turns; deflating the tire to 26 psi greatly reduced this tendency. The proof that it wasn't a "tire issue" is the fact that the same year models of the Chevy S10 Blazers used the exact same size and model of tire WITHOUT any incidents of blow outs. Why the difference? The Blazer tires was factory recommended to have 35 psi. Both the Blazer and Explorers were similar in weight so that's not a variable. Later generations of the Explorer became wider, lower and heavier which allowed them to increase the tire pressure without having the tendency to roll over. Bottom line is if Ford wanted to run that low pressure for that heavy of a vehicle, they should have picked a tire that was Temperature rated "A". Then, the blow out problems wouldn't have occurred. To be fair, Firestone DID find one location that produced that size Wilderness A/T tires that used a different method of applying the adhesive to bond the tread to the carcass; they stopped production at that location. However, a lot of the tires that failed were not only from that location so it shows that the tire application was improper, not how the tires were made.

Which goes to show that, contrarily to popular belief, the manufacturer's sticker must not always be taken as gospel.

 

[Bikeman315]

Which goes to show that, contrarily to popular belief, the manufacturer's sticker must not always be taken as gospel.

Vlad, this was one issue over 20 years ago. Do not throw out the baby with the bath water. Todays manufacturers recommendations are solid and should be followed.

 

[Vlad Soare]

Todays manufacturers recommendations are solid and should be followed.

Maybe, although I still have some doubts. Ford recommending different pressures for the same car in different markets, among other things, does make me raise an eyebrow.
I think the door sticker pressures are a good starting point, but adjustments may be needed on a case by case basis. For instance, if I started with their recommended pressure and then I saw a 6 psi increase after driving fast for half an hour on a summer day, that would be a clear indication that the starting point was too low. Trust the manufacturer, but not religiously.

 

[Bikeman315]

Maybe, although I still have some doubts. Ford recommending different pressures for the same car in different markets, among other things, does make me raise an eyebrow.
I think the door sticker pressures are a good starting point, but adjustments may be needed on a case by case basis. For instance, if I started with their recommended pressure and then I saw a 6 psi increase after driving fast for half an hour on a summer day, that would be a clear indication that the starting point was too low. Trust the manufacturer, but not religiously.

OK, you lost me. If you start with the recommended 33PSI and it increases by 6 PSI you’re at 39. That’s just fine for the high speed running in hot temperatures. You certainly would not want to run higher. Once you slow down the pressure should return to the normal +3/4 lbs. IF anything you would want to lower the PSI to keep the tire in the 36/37 PSI. But as already mentioned under inflation is the cause of most tire related issues and would not be recommended.

 

[Vlad Soare]

I mean if the pressure increases while driving by a large amount, then it means it was too low to begin with. There is always friction in the tire, which makes an increase in pressure unavoidable. But underinflation causes extra friction, which increases the pressure even more. A big increase is a sign of underinflation.
If you start with 33 and end up with 39, then maybe you should try 35 next time. If you start with 35 and end up with 38, that means that 33 was too low.

In my case, 33 cold increases to about 36 warm, which seems fine.

 

[Bikeman315]

I mean if the pressure increases while driving by a large amount, then it means it was too low to begin with. There is always friction in the tire, which makes an increase in pressure unavoidable. But underinflation causes extra friction, which increases the pressure even more. A big increase is a sign of underinflation.
If you start with 33 and end up with 39, then maybe you should try 35 next time. If you start with 35 and end up with 38, that means that 33 was too low.

Gotcha. We both agree that under inflation is bad.

 

[Garfy]

Which goes to show that, contrarily to popular belief, the manufacturer's sticker must not always be taken as gospel.

Amen to that!

 

[Garfy]

Vlad, this was one issue over 20 years ago. Do not throw out the baby with the bath water. Todays manufacturers recommendations are solid and should be followed.

I think that the general idea is that over-inflation by a certain amount is better/safer than under-inflation by that same amount. As an example, it's generally better to be over-inflated by 5 psi than under-inflated by 5 psi (assuming you don't exceed the general P-metric passenger tire maximum of 44 psi). The over-inflation will give you a harsher ride but the under-inflation will generate excessive heat especially in the sidewalls which flex so much more than normal and that's where the heat is concentrated. Too much flexing will cause the sidewalls to deteriorate and eventually shred resulting in the carcass failure.

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