The best way to gauge "empty" pressure is the chalk test.
Get a piece of chalk (I use my grandaughter's sidewalk chalk) and draw a wide line across the tire tread. Then drive the truck a few feet and see how much of the chalk came off. Adjust your pressure up or down to get as much of the line off as possible.
The quicker way is visually. Let air out until the bulk of the tread looks like it's sitting flat. Then drive it and see if it's too squirrelly.
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Jay
"0-60 takes 5 and a half seconds...and about 17 gallons of fuel...."
Tire size and construction matter a lot. My E rated 315/75-16's can have as little as 25 psi and have acceptable load capacity. A 235/85-16 D rated tire will need a lot more....
Go to the tire manufacturer's website and see if they have load capacity tables for your tire model and size. Put enough air in the front tires to support at least 2000 pounds each, and for the rear, at least 1500 pounds each and you should be pretty close to good.
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'99 F250 V10 Super Cab Long Bed 4x4. '06 short block, PI conversion, modded airbox, 5 Star custom tune, FM50BB, 315/75-16 GY Duratracs, mild lift, 4.30 LSD, Ride-Rite bags, on board air, Rancho RS9000 w/MyRide, under bed subwoofer.
Why, yes, I am some kind of a geek engineer. Thank you for asking.
What does the tire say on the side? Keep in mind, tires could have been switched out for another set which may not go as high as what the door sticker says. You never want to exceed the pressure marked on the side of the tire. For instance, my tires have a max rating of 50psi but my door sticker says 65psi.
As for how much air to put in them, the chalk or grease pen test as Barthel described is the best way to find out what pressures work best for an unladen truck versus a laden truck.
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Shaun
Quote:
Originally Posted by George Bush
Wait, what did you just say? You're predicting $4 a gallon gasoline?. . . That's interesting. I hadn't heard that.
Another good tire pressure test is the IR thermometer. It works best when it's warmer outside, but drive at highway speeds for awhile, then get out and measure the temperature across the surface of the tire. If it's hotter in the center than the edges, you have too much pressure. If it's hotter on the edges than in the middle, you have too little pressure. Once you figure out what pressure you need empty, remember it. Then remember if you take on a load you'll want more pressure.
If you tow a trailer or carry a specific load (like a camper) regularly, do the tests with the load and get the right pressures for that load.
FYI, running empty I find 60 PSI to be adequate, although actually it is a little high. I run stock size 265/75R16 Toyo A/T's. 55 PSI is probably closer to what I need, I just can't bring myself to run them that low. Believe it or not, my door sticker says 55 PSI front, 75 PSI rear.
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David Chamberlain
2004 F-250 SD, 4x4 FX4, 6.0L PSD
Oregon Chapter Member: To join the Oregon Chapter, click HERE
Forgot to add I'm running BFGoodrich Rugged Trails, LT265/70R17's, they list MAX as 80psi.
Was running 55psi when I got home with her, have adjusted them all to 60 for now, probably drop them back to 55 until I get the chance to do the chalk test.
Also, she was a southern truck and antifreeze was good to +5, now @ -40.
I always thought that Ford Pickups were the BEST!, but I'll never own another one. Not since I've driven a Ford Truck!
Forgot to add I'm running BFGoodrich Rugged Trails, LT265/70R17's, they list MAX as 80psi.
Was running 55psi when I got home with her, have adjusted them all to 60 for now, probably drop them back to 55 until I get the chance to do the chalk test.
Also, she was a southern truck and antifreeze was good to +5, now @ -40.
I always thought that Ford Pickups were the BEST!, but I'll never own another one. Not since I've driven a Ford Truck!
HAVE YOU DRIVEN A FORD LATLEY?!
Dan B.
Central Ks.
. Hummmm.
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RICK, PAA MEMBER #4
2001, F-350, DRW. CC. LWB, 4X4, LARIAT,
MODS: 6637 W/Pete's cover, BTS-TRANS, DP-TUNER LIVE, MBRP 4" SS, Isspro 3 gauge kit, TN-BB turbo, Bellowed up pipes, HPX, TRU-COOL cooler, SS Stage II injectors, and the Chris-fifty.
What's the difference between a pickup and a truck?
__________________ Jim-2004 Crew Cab V10 4x4
Never be afraid to try something new. Just remember, amateurs built the Ark, professionals built the Titanic...
Ford has spent millions of dollars designing the truck, their engineers know the correct pressure.
Whatever the manufacturer of the vehicle says the air pressure should be is the correct pressure.
I don't think it's that simple. The correct pressure for any given tire depends on the weight being carried by that tire. Since Ford doesn't know how much weight you're going to be carrying at any given time, it's pretty hard for them to determine the "correct pressure" at any given time. Generally the pressures they recommend are for the tires when the axle is at Gross Axle Weight Rating. Since few people are always carrying GAWR around, the correct pressure is often much less than what the sticker says.
Different tires often also requires different pressure. Again Ford can't predict what brand tire you may put on in the future, so it's impossible for them to determine the correct pressure.
Ford's recommended tire pressures are for their tires at what they figure the maximum weight should be. And I'd be willing to bet with a little extra thrown in for liability protection. If you want the best life and performance out of your tires, it's a good idea to understand tire flexing, what overpressure and underpressure does, and figure out how to determine what the correct pressure is for YOUR situation, not Ford's hypothetical one.
__________________
David Chamberlain
2004 F-250 SD, 4x4 FX4, 6.0L PSD
Oregon Chapter Member: To join the Oregon Chapter, click HERE
I don't think it's that simple. The correct pressure for any given tire depends on the weight being carried by that tire. Since Ford doesn't know how much weight you're going to be carrying at any given time, it's pretty hard for them to determine the "correct pressure" at any given time. Generally the pressures they recommend are for the tires when the axle is at Gross Axle Weight Rating. Since few people are always carrying GAWR around, the correct pressure is often much less than what the sticker says.
Different tires often also requires different pressure. Again Ford can't predict what brand tire you may put on in the future, so it's impossible for them to determine the correct pressure.
Ford's recommended tire pressures are for their tires at what they figure the maximum weight should be. And I'd be willing to bet with a little extra thrown in for liability protection. If you want the best life and performance out of your tires, it's a good idea to understand tire flexing, what overpressure and underpressure does, and figure out how to determine what the correct pressure is for YOUR situation, not Ford's hypothetical one.
I understand there are variables in the way a vehicle is used and loads it carries, Ford and their multitude of engineers take all of that into account when designing a vehicle.
They are the ones who know how to determine the proper tire pressure.
My father was in the tire business for quite awhile, he always said to follow the automobile manufacture's advice on tire pressure, as the vehicle was designed to be run at that pressure.
Not my vehicle so I don't care what tire pressure you guys run.
What exactly did your father do in the tire business that made him feel the tire engineers weren't as trustworthy as the vehicle engineers? I'm sure Ford does have lots of engineers on staff. Those same engineers felt the 6.0 was a suitable replacement for the 7.3 and that four threads were more than enough to hold a sparkplug in place in the modular motors. Ford's engineering staff are not the last word in tires, if they were, then Ford would produce it's own tires, just like they now produce their own diesel engines
__________________ Jim-2004 Crew Cab V10 4x4
Never be afraid to try something new. Just remember, amateurs built the Ark, professionals built the Titanic...
What exactly did your father do in the tire business that made him feel the tire engineers weren't as trustworthy as the vehicle engineers? I'm sure Ford does have lots of engineers on staff. Those same engineers felt the 6.0 was a suitable replacement for the 7.3 and that four threads were more than enough to hold a sparkplug in place in the modular motors. Ford's engineering staff are not the last word in tires, if they were, then Ford would produce it's own tires, just like they now produce their own diesel engines
The engineers at the automobile manufacturer's know more about tire pressure requirements for vehicles they design than anyone else, including internet professional's.
Tire manufacturers do not design vehicles.
The 6.0 replacing the 7.3 was due to the federal government emission standards, and you can thank uncle sam, the epa and the tree hugger's for that one.
The Ford engineers are the ones to listen to when it comes to tire pressure on vehicles they design and build, not a tire manufacturer or an internet 'guru'.
Ford does not produce a lot of parts they use, but they have to meet their specs.
My father worked for a company that sold, leased and serviced tire equipment.
What exactly did your father do in the tire business that made him feel the tire engineers weren't as trustworthy as the vehicle engineers? I'm sure Ford does have lots of engineers on staff. Those same engineers felt the 6.0 was a suitable replacement for the 7.3 and that four threads were more than enough to hold a sparkplug in place in the modular motors. Ford's engineering staff are not the last word in tires, if they were, then Ford would produce it's own tires, just like they now produce their own diesel engines
Compare the measured psi to the psi found on the stickerinside the driver’s door of your vehicle or in owner’s manual. DO NOT compare to the psi on your tire’s sidewall.
I think Michelin agree's what what I said as well as what my father said.
The first place to look for the correct air pressure for your specific tires is your vehicle owner's manual. Correct air pressure should also be listed on the tire placard attached to the vehicle door edge, doorpost, glove box door or fuel door. You may use the tool above to view the manufacturer recommended inflations for standard sized tires on your vehicle.
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. Ford® is a registered trademark of the Ford Motor Company.
. Hummmm.
