This is just because some folks do not know this. The recommended tire inflation pressure on the plate when you open the door may or may not have anything to do with the tires you are running on your truck. Keep this in mind when you buy replacement tires--it can change
Yep, this used the bother the heck out of me when I had my Ram. Once the OEM tires needed replacing, I had swapped from running the stock P tires it came with to a set of LT tires (Max cold 80 psi, ran them around 65-70 psi street and aired up for towing). Every Single Time it went into the dealership for it's routine maintenance, the tires always came back deflated down to the door pillar's 35 psi recommend for the P tires I had replaced.
That is correct. My personal real world experience with that 2015 F 150.
To obtain even tire wear on my 2010 F150 FX4 I ran 42# in the 20" tires. Currently running 40# in wife's 2018 Explorer Ltd after getting poor tire wear at 35# in her 2013 Explorer Ltd (both with 20" wheels). I ran 72# in both V10 Excursions and tire wear was good. Also running 72# in my 2017 F250 6.7L KR since it weighs about the same as the Excursions. I once got 96k miles out of a set of E-rated BFG tires on my '87 F350 CCLB SRW running 72#, but that truck only weighed ~5,000# (same as the 2010 F150).
Yep, this used the bother the heck out of me when I had my Ram. Once the OEM tires needed replacing, I had swapped from running the stock P tires it came with to a set of LT tires (Max cold 80 psi, ran them around 65-70 psi street and aired up for towing). Every Single Time it went into the dealership for it's routine maintenance, the tires always came back deflated down to the door pillar's 35 psi recommend for the P tires I had replaced.
The load curve for LT tires is not significantly different except that it extends further. So, at modest loads, it is not inherently necessary to run significantly higher pressures than with lesser tires.
The load curve for LT tires is not significantly different except that it extends further. So, at modest loads, it is not inherently necessary to run significantly higher pressures than with lesser tires.
Pic is from Toyo Tires.
Hmm, are we sure we're talking apples to apples here? I went from P tires to LT tires. Everything I've ever heard or read on this kind of change was that you don't run an LT at the same pressure you ran a P. I'll admit I probably could have ran them softer than I was, but no way was I running them as low as 35 psi. The tire didn't even look round at that low of a pressure. It had the bulging sidewall look of a severely under inflated tire when it was at 35.
Hmm, are we sure we're talking apples to apples here? I went from P tires to LT tires. Everything I've ever heard or read on this kind of change was that you don't run an LT at the same pressure you ran a P. I'll admit I probably could have ran them softer than I was, but no way was I running them as low as 35 psi. The tire didn't even look round at that low of a pressure. It had the bulging sidewall look of a severely under inflated tire when it was at 35.
Of course, I always defer to the chalk test--or the next best thing of the "eyeball" test. But, all of the E-rated charts I have seen still go down to very modest pressures at modest loads. For example, the official chart I found for my OEM tires actually lists 35 PSI for a 1770lb load. That is 3540lb on the axle, which is 800lb more than the factory rear axle weight on my truck.
I have about 600# of fuel and tools in the bed at any given time and run 60psi all the way around. A strip of wide masking tape across the tread for a few miles tells me the wear is biased slightly to the middle of the tread but have good contact all the way across. I'm happy with that.
Excellent question. Any one care to comment as I just picked up my truck yesterday.
I have a 2019 Lariat F-350 6.7l 4x4 CCSB SWR that I picked up in mid-December. I ran a test on the TPMS sensors because I wanted to know when they went off. I had heard variations of -10psi to -25% before they went off; there was nothing in the owner’s manual describing this. My TPMS indicator light in the dash illuminated at -35% which equates to 52psi on the rear down from 80psi and 42psi on the fronts down from 65psi. I have not tried any other starting pressures to confirm the 35% figure, but I’m betting that value is the same on all 2019’s.
I have a 2019 Lariat F-350 6.7l 4x4 CCSB SWR that I picked up in mid-December. I ran a test on the TPMS sensors because I wanted to know when they went off. I had heard variations of -10psi to -25% before they went off; there was nothing in the owner’s manual describing this. My TPMS indicator light in the dash illuminated at -35% which equates to 52psi on the rear down from 80psi and 39psi on the fronts down from 65psi. I have not tried any other starting pressures to confirm the 35% figure, but I’m betting that value is the same on all 2019’s.
Just took delivery of mine a week ago. Same truck as yours. Mine went off on the left rear at 66psi, right rear has 67psi and hasn't set TPMS off.
Just took delivery of mine a week ago. Same truck as yours. Mine went off on the left rear at 66psi, right rear has 67psi and hasn't set TPMS off.
Thank you for the information. I will do another test on mine in a couple months when I get back to my compressor. I only ran one test, on one front and one rear tire. I measured the starting pressure and let air out as an observer was watching the dash for the low pressure light to come on. Quite honestly, I won’t be too surprised if the TPMS sensors that Ford installs are not consistent. If this is the case and you care about the tire pressure when your LOW PRESSURE SENSOR LIGHT turns on, I suppose you will have to run your own test to see what the trigger pressure is. I will update this, but it isn’t happening until late March.
Thank you for the information. I will do another test on mine in a couple months when I get back to my compressor. I only ran one test, on one front and one rear tire. I measured the starting pressure and let air out as an observer was watching the dash for the low pressure light to come on. Quite honestly, I won’t be too surprised if the TPMS sensors that Ford installs are not consistent. If this is the case and you care about the tire pressure when your LOW PRESSURE SENSOR LIGHT turns on, I suppose you will have to run your own test to see what the trigger pressure is. I will update this, but it isn’t happening until late March.
Not sure about the ones on the Ford, but the ones on my Ram only updated once they were rolling for a few minutes. Usually by the time I hit the end of the block. If the Ford's are the same, then you might have gone past the low pressure point way before your dash knew about it. When you try this again, either take a drive in between letting a little air out, or jack up the truck and spin the wheel by hand in between letting a little air out and see when it trips that way.
Not sure about the ones on the Ford, but the ones on my Ram only updated once they were rolling for a few minutes. Usually by the time I hit the end of the block. If the Ford's are the same, then you might have gone past the low pressure point way before your dash knew about it. When you try this again, either take a drive in between letting a little air out, or jack up the truck and spin the wheel by hand in between letting a little air out and see when it trips that way.
My '19 F-350 is the same way. No alarm at ~62psi for days when sitting and putting around town. Then all four alarmed when on the highway...
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01-20-2019, 11:14 PM
