Tire Pressure Question
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Mountain Pass
Joined: Aug 2019
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Tire Pressure Question
Hi all. I have a ‘19 F350 Powerstroke Crew Cab short bed XLT. I put 35-12.50-18s BFG AT/KO2s on it. The pressure on the tire says 65psi Max, but the dealer said the rear tires should be at 80 no matter what the tire says. Is that right? I thought the tire psi recommendation was the rule. I tow a 11k lb travel trailer and golf cart with about 2500 lb total bed/tongue weight. I only had it checked because the TPMS sensors tripped on both rear tires.
More Turbo
Joined: Jun 2020
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From: Texas Hill Country
Go by the tire rating, not the truck sticker, because you can put any tire on a truck. That truck should have E rated tires, which should hold 80, but if the tires are not E tires, then go with what the sidewall says. Also, most people with tires that hold 80 don't keep that much air in them in unless they need it for load capacity.
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Mountain Pass
Joined: Aug 2019
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Does that have to be done at the dealer? They did not even offer that option.
Fleet Mechanic
Joined: Oct 2012
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From: NorCal
My F 350 sticker shows 60 psi in front and 80 psi for rears. I run empty with 50psi in front and 65-68 in rears. No TPMS lights
As for your tires, my Toyo MT E rated tires had a max air of 60 so that's what ran them at... I would not exceed the tire manufactures ratings IMO
As for your tires, my Toyo MT E rated tires had a max air of 60 so that's what ran them at... I would not exceed the tire manufactures ratings IMO
Hotshot
Joined: Oct 2015
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From: Wyoming
It sounds like you have a D rated tire on a truck that came with an E rated tire. The dealership may balk at making any changes for you because of that.
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From: Media PA
Go by the tire rating, not the truck sticker, because you can put any tire on a truck. That truck should have E rated tires, which should hold 80, but if the tires are not E tires, then go with what the sidewall says. Also, most people with tires that hold 80 don't keep that much air in them in unless they need it for load capacity.
I disagree that any "E" rated tire (an outdated rating system, but for this discussion I think everyone understands the intent) should have an 80 PSI rating. The max inflation is a function of the contact patch vs the intended weight carrying capacity, a larger, wider tire (like the OP stated that he has) will have a lower max pressure due to having more square inches in its contact patch, in this case it maxes out at 65 PSI. My 305/70R18 (35.28X12.8) Nitto Duras, which are "E" rated are the same 65 PSI max inflation but have a higher weight rating than the stock 265/75R16 tires that they replaced, even at that lower pressure.
The OP's dealer, who stated the tires needed to be at 80 PSI no matter what the tire sidewall stated is a dangerous idiot.
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Mountain Pass
Joined: Aug 2019
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Yes, go by the tire rating and don't inflate above the sidewall max ratings. Better yet go by the scaled axle weights and a tire inflation weight table provided by the tire manufacturer, that's the best course of action to get the exact right inflation for the load.
I disagree that any "E" rated tire (an outdated rating system, but for this discussion I think everyone understands the intent) should have an 80 PSI rating. The max inflation is a function of the contact patch vs the intended weight carrying capacity, a larger, wider tire (like the OP stated that he has) will have a lower max pressure due to having more square inches in its contact patch, in this case it maxes out at 65 PSI. My 305/70R18 (35.28X12.8) Nitto Duras, which are "E" rated are the same 65 PSI max inflation but have a higher weight rating than the stock 265/75R16 tires that they replaced, even at that lower pressure.
The OP's dealer, who stated the tires needed to be at 80 PSI no matter what the tire sidewall stated is a dangerous idiot.
I disagree that any "E" rated tire (an outdated rating system, but for this discussion I think everyone understands the intent) should have an 80 PSI rating. The max inflation is a function of the contact patch vs the intended weight carrying capacity, a larger, wider tire (like the OP stated that he has) will have a lower max pressure due to having more square inches in its contact patch, in this case it maxes out at 65 PSI. My 305/70R18 (35.28X12.8) Nitto Duras, which are "E" rated are the same 65 PSI max inflation but have a higher weight rating than the stock 265/75R16 tires that they replaced, even at that lower pressure.
The OP's dealer, who stated the tires needed to be at 80 PSI no matter what the tire sidewall stated is a dangerous idiot.
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More Turbo
Joined: Oct 2020
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Yes, my 35" Dynapro's have a higher weight capacity than stock with a 65# max psi, very common in an E rated 35" tire.
I actually performed a chalk test on garage floor and run 47 in front and 40 in back empty.
Albeit this is a Ram 2500 5.7......while I'm waiting on my F250 to arrive.
I actually performed a chalk test on garage floor and run 47 in front and 40 in back empty.
Albeit this is a Ram 2500 5.7......while I'm waiting on my F250 to arrive.
More Turbo
Joined: Oct 2020
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Do these trucks not have a TPMS teach function? My cars i just hold down the TPMS button for a few seconds and then it goes into teach mode, after about a mile it sets to the new pressure? The TPMS should just be a +/- range of the set point.
Senior User
Joined: Jan 2012
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Fords all use sensors at this point. Cars with buttons are generally using wheel speed sensors and the ABS system..
An Autel TS508 tpms scanner can set the tpms threshold as well. I do it about daily for various trucks
An Autel TS508 tpms scanner can set the tpms threshold as well. I do it about daily for various trucks
Hotshot
Joined: Oct 2015
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From: Wyoming
I have an Autel TS601. I haven't looked for it, but I wonder if mine can set the threshold also. What I really want is a way to adjust the reported PSI from the sensor. I have a set of sensors that consistently report 3 PSI below what a number of my digital gauges say.
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601 may have it. On a 508 it's under "Set TPMS Threshold" in the main advanced screen for most any Ford/Chevy/ Dodge product. It does not work on most dodges as it creates error codes. Anyway, the sensors themselves are almost never perfectly accurate, and they will display whatever they display but that firmware is embedded within the sensor.
Hotshot
Joined: Oct 2015
Posts: 19,676
Likes: 12,797
From: Wyoming
601 may have it. On a 508 it's under "Set TPMS Threshold" in the main advanced screen for most any Ford/Chevy/ Dodge product. It does not work on most dodges as it creates error codes. Anyway, the sensors themselves are almost never perfectly accurate, and they will display whatever they display but that firmware is embedded within the sensor.
