Tire pressure sensor

[J Ski]

Not really sure how these work. I plan on going up to 285/65/20s (34.80x11.50) Nitto ridge grapplers which require 80psi. Will I need to have computer calibrated to read those higher pressures or is that something the shop does when they install the new pressure sensors.

 

[JExpedition07]

If they require 80 psi you may need new sensors, when i had mine replaced the Ford OEM units i bought were for 50 psi max i think it was printed on them and they are programmed to warn the truck below a certain interval like around 30 psi, which is way low on a tire requiring 80 meaning they’d pretty much be rendered useless.

 

[AllBoostNoEco]

Your stock sensors will be just fine. Mostly because you shouldn’t be anywhere near 80 PSI with those tires. They’d be WAY overinflated. Still, I measured mine once and they were at 51.5 PSI hot and my computer didn’t seem to care.
I’m not gonna rehash the entire previous discussion about inflation pressures in LT tires, but all you need is 36 PSI to match stock load rating on that particular size LT tire.

 

[ExpeditionAndy]

If I remember correctly you can change the tire pressure setting in the computer by using FORScan, particularly if you want to raise the low pressure setting.

 

[07xln]

Your stock sensors will be just fine. Mostly because you shouldn’t be anywhere near 80 PSI with those tires. They’d be WAY overinflated. Still, I measured mine once and they were at 51.5 PSI hot and my computer didn’t seem to care.
I’m not gonna rehash the entire previous discussion about inflation pressures in LT tires, but all you need is 36 PSI to match stock load rating on that particular size LT tire.

He’s buying an E rated tire that at max load require 80psi. While I agree he shouldn’t run 80psi especially if not hauling or towing anything. 80psi is hardly over inflated for that tire but 36psi is very under inflated

I would run 55-60 in those tires

 

[AllBoostNoEco]

Stock tire size is P275/55R20, which is load rated at 2403 pounds at 35 PSI in a passenger car application. Since it’s on an SUV, you divide that by 1.1 due to downrating of P-metric tires in an SUV/light truck application. That gives you 2,185 pounds at 35 PSI.

The tire he is replacing it with is an LT285/65R20, which supports 2,180 pounds at 35 PSI. At 36 PSI, it supports 2,222 pounds. Thereby putting it slightly over the requirement for this application.

This info all came from the Tire and Rim Association Load application tables, which is the standard used by all tire and rim manufacturers in the US to rate their respective items.

I wanted to put this out there because there are always a lot of questions about how you truly determine proper inflation for an LT-metric tire in an application originally fitted with a P-metric one.

 

[07xln]

36psi is still under inflated for an E rated tire

 

[AllBoostNoEco]

I get your point, I was the one arguing that LT tires always need more pressure than a P-metric tire in the other tire thread

This just happened to be one of those rare instances where it actually doesn’t. I expected more in the neighborhood of 42-43 PSI, but even I can’t argue with the trade association.

 

[JExpedition07]

I’m not good with tires, i know In my F-350 it’s clearly printed on the side the tires want 80 PSI. for a truck tire 80 psi is not overinflated. My Expedition requires 35 psi. The 350 runs a 10 ply tire though not sure how that factors in to psi ratings. I was just pointing out that if the max on the Sensor like mine is 50 PSI, no change can be made with the computer that will make the Sensor comply with an 80 PSI tire. The sensors on the expesition aren’t made to go that high, it’s printed right on them after all.

 

[AllBoostNoEco]

I’m not good with tires, i know In my F-350 it’s clearly printed on the side the tires want 80 PSI. for a truck tire 80 psi is not overinflated. My Expedition requires 35 psi. The 350 runs a 10 ply tire though not sure how that factors in to psi ratings. I was just pointing out that if the max on the Sensor like mine is 50 PSI, no change can be made with the computer that will make the Sensor comply with an 80 PSI tire. The sensors on the expesition aren’t made to go that high, it’s printed right on them after all.

You’re absolutely right about the tire sensors, I have no idea what my stock sensors are capable of handling, but I know when I was towing and had 50 in them and saw 51.5 hot, I didn’t get any warnings for sensor problems. I wonder if the sensor just maxes out and loses it’s ability to effectively measure pressure above the rated range? This requires more investigation.

There is a big difference between max and proper inflation pressure. The numbers on the side of the tire actually have virtually nothing to do with proper inflation pressure. That’s just what the tire is capable of.
What does your door sticker for your F-350 say for proper inflation pressure?

The ply rating usually refers directly to load rating. There are XL P-metric tires, load range D, and load range E tires; and generally 10-ply all fall into load range E.

 

[JExpedition07]

I’ll take a double take on the 350 door sticker in the morning, couldn’t tell you what it calls for to be honest on there. I generally run them at 65ish psi but i remember reading 80 on the side, but your right that is probably max inflation pressure rating. Being a 1 ton it doesn’t have the best ride and at 80 the truck literally rode like a horse carriage on a trail. Also i don’t believe the TPMS will alert us of an overfill i believe it’s only a low pressure warning.

 

[AllBoostNoEco]

I’ll take a double take on the 350 door sticker in the morning, couldn’t tell you what it calls for to be honest on there. I generally run them at 65ish psi but i remember reading 80 on the side, but your right that is probably max inflation pressure rating. Being a 1 ton it doesn’t have the best ride and at 80 the truck literally rode like a horse carriage on a trail. Also i don’t believe the TPMS will alert us of an overfill i believe it’s only a low pressure warning.

I do believe you’re correct on the sensors. I can’t find anything on sensor specifications for cars, but I found a bunch for tractor-trailers, and all of them specify a range the sensor is capable of reading. There’s no warnings about exceeding that range causing damage, which leads me to believe above the max pressure the sensor maxes out and will tell the computer whatever the highest it’s rated for regardless of how high it actually is. An over inflation warning would have to be programmed in, and since under inflation is more of an issue than over, doubt they went to the trouble.

 

[Muddy Bean]

Tire pressure threads. Ugh. I agree, you really need to study the tire manufacturers inflation tables for load and fill to the pressure they recommend if you want to be a tire geek. That being said, I have always slightly overinflated my tires and have experienced amazing long treadwear out of every set. Always rotate them in a timely manner and get the truck 4 wheel alignments somewhat often and you’ll be happy. My KO2’s can handle something in the 65 or 70psi range but I don’t run them that inflated. I run them around 45-50 psi. Right now I’m towing a tractor and trailer so I inflated them a little more than usual to handle the extra tongue weight.


Sent from my iPhone using Tapatalk Pro

 

[JExpedition07]

My sticker says 65 PSI for all four on the door jamb on the SD.

 

[chuck s]

Ply and load ratings are 1930's nomenclature dating back to when tires actually had 6, 8, 10 or more plies stacked in the tread. Maximum tire capacity in pounds is easier to understand and is molded into the tire sidewalls. Running tire pressure is more complex than maximum capacity and has factors like tread on the road and ride comfort.

And a reminder the suspension components will be overloaded long before the tires on this vehicle.

-- Chuck