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Old 02-08-2017, 02:02 PM   #21
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Tire Pressure

Tire pressure is extremely important. Many RVers inflate their tires incorrectly. I suggest that you contact RVSEF (Recreation Vehicle Safety & Education Foundation) RVSEF - RV Weighing & Safety Education and solicit their advice. They also offer classes and actually weigh RV's (at each wheel) at seminars across the country.
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Old 02-08-2017, 02:40 PM   #22
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Quote:
Originally Posted by bkool2323 View Post
2015 Ford F150 Lariat SuperCrew.
Michelin LTX A/T load range E sidewall 80 psi

When towing air up to 65 rear 60 front

Daily driving 47psi all around.

At 80psi all around I would feel like Fred Flinstone.
X2

When I had my F-150, I put on a set of Michelin LTX M/S LRE tires (no longer available). The factory P tires were inflated to 35 psi, but I ran all 4 LT's at 50 psi as a daily driver and went to 65 psi on all 4 when towing. They were a good tire and I have the A/T version on my new F-250, but when they wear out, I'm going back to the Bridgestone Dueler A/T Revo 2 tires I had previously. The tread and grip are better in the winter.
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Old 02-08-2017, 02:48 PM   #23
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Originally Posted by 2Evil4U View Post
I run OEM recommended pressure for daily driving, max sidewall for towing.
x2
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Old 02-08-2017, 02:56 PM   #24
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I use the manufactures recommendations for truck and camper. Has worked well, over the years. Later RJD
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Old 02-08-2017, 03:04 PM   #25
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Originally Posted by aceinspp View Post
I use the manufactures recommendations for truck and camper. Has worked well, over the years. Later RJD
X2
Many tire manufacturers list tire pressures for given loading rates.
Just because a tire should be inflated to its maximum pressure to handle the maximum load doesn't mean that you can't drop the pressure when loaded less.

This typically never applies to an RV tire as they are always dangerously tipping the overload point empty.

Your tow vehicle tires are a somewhat different story.
Here is a Michelin chart.
**INFLATION CHARTS**
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Old 02-08-2017, 03:32 PM   #26
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OEM pressure as listed on the door tag is great as long as you run the same tire and wheel for the life of the vehicle. If you change tires and wheels like many of us do, than you need to do your homework for the new stuff.
I air up and air down; 80psi even on a F250 rattles my bones when it is unloaded.
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Old 02-08-2017, 03:38 PM   #27
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In my opinion, the question was presented backwards. It should have been "Do you decrease tire pressure when not towing?". You MUST have enough PSI in your tires to carry whatever load you are asking of it. You don't necessarily have to reduce that PSI when your between the heavier loads.


I keep my trucks tires aired up to the correct minimum PSI (plus a little) for my towing needs. I occasionally will reduce the PSI if I am either planning a long "unloaded" trip (for comfort), or am heading to the snow (for traction). This works well for me, but I don't drive the truck unloaded very often...it spends the majority of it's time waiting for the next camping trip (just like me!).


PS...80 PSI in an unloaded F-150....yikes!!
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Old 02-08-2017, 03:39 PM   #28
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Originally Posted by dalford View Post
X2, lbrjet.. do you have the inflation table for those tires or is it standard for all E rated tires? The OP might like to see that so he can then inflate his tires accordingly for towing vs non-towing..


Tire size and diameter.

I the toyotire inflation table pdf you can find online.
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Old 02-08-2017, 04:41 PM   #29
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During the towing season, i inflate all tires to the sidewall max PSI and leave them be. My truck handles much better towing. When i park the camper for the year, i deflate 5 PSI for a smoother ride.
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Old 02-08-2017, 05:16 PM   #30
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45 day to day. 65 rear and 45 front towing. Works very well with my truck and trailer. Opinions vary.
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Old 02-08-2017, 05:38 PM   #31
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Do you increase tire pressure when towing?

Quote:
Originally Posted by LJS1211 View Post
Last week I purchased new E rated tires for my F150. Went with the BF Goodrich KO2 (275/65/18) and so far I'm very happy with them. These are larger than the tires that came from the factory (265/60/18). I'm pulling my trailer for the first time this weekend so had a quick question.

The tire shop originally put the PSI at 35 based on the door sticker but after reaching about to BF Goodrich they suggested to bump it up to 45 for everyday driving. They were not able to give any recommendations for tire pressure while pulling a trailer since there are so many variables like trailer size, weight and cargo. The tire shop suggested going to 50 pounds and then deflating back down after the trip. I'm just curious if others actually bump up their PSI while towing and have you noticed a difference in doing this? Just trying to figure out if there is a benefit to doing this. Thanks in advance for your feedback.


I bought the same tires, same size, two months ago for my F-150. Out of curiosity I emailed BF Goodrich and this is what I got back;

"When installing a different size than the original equipment tire, all vehicle manufacturer specifications must be maintained. The replacement tire should be inflated to provide the same load capability of the original tire size at the manufacturer’s recommended pressure.
Ryan, thank you for recent purchase of All-Terrain T/A KO2 tires. We would recommend that you inflate your tires to a psi of 55, at this pressure your new tires would exceed the original tires load carrying capacity."

It probably depends who your talking to or emailing with. I tried them at 50 psi and found them too hard. Currently inflated to 40 and much more enjoyable ride for every day driving. Towing local I'll leave them at 40, for long distance I'll increase the psi.
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Old 02-08-2017, 09:48 PM   #32
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Originally Posted by chrisf65 View Post
Just to remind everybody- he is NOT driving a HD 2500 or 3500 dually- it's a F150 halfton truck! The tire pressures are not as high there. a half ton bounces like a rubber ball with 70psi on the rubber.
In post#3 you told him to run what the sidewall says, he stated that it was a load range E tire. If I'm not mistaken all load range E tires have a max psi of 80 stamped on the tire. And yes it will ride rough, Especially with the BFG KO2's they are not a very soft forgiving tire.
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Old 02-09-2017, 08:47 AM   #33
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Picked up my truck with 80psi Nitrogen front and rear.. keep it that way and adjust only for seasonal temperature change..
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Old 02-09-2017, 11:23 AM   #34
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Also I as "pigheaded Dutch selfdeclared tirepressure-specialist" need to know real weights on tires, before I can give a pressure advice.

But in front , I can give some things to keep in mind.
First, probably Your OEM tires are P-tires in Standard load, because they have a pressure needed for maximum load of 35 psi, and most car makers nowadays give that as advice pressure.

Then you would expect because of the much more maximum load and the bigger tire, that the needed pressure to give same savety as old tires, need lower pressure.

For the sises this is the case, but because of the E-load AT 80 psi , because they are stiffer, need higher pressure . My estimation is that both compensate each other and so you can do with 35 psi, but realise this is a dangerous idea.

Then your front tires wont get more weight on when towing, the front axle is lifted up a bit , by leaver effect of the tonge weight of trailer.
So you only need to pump up the rear tires when towing and leave the front as they are.

Also speed is lower ( here in Europe, but mayby you also are allowed to drive 80m/h with a heavy trailer behind).

Lower speed also allows lower pressure.
Pressure advice is to give the tire a deflection that wont produce to much heat, so rubber stays below a sertain temperature , where it hardens and crackes in next bendings/deflections.
This heatproduction is a product of ( X) number of cycles a second X heatproduction ( so deflection) per cycle.
So lower speed allows more deflection so lower pressure for the same load.

Then the pressure advice of newer cars ( after the year 2000) is higher then you would calculate for the load , and in fact this is that save, but means that you can do with lower, if you know all the data 100% acurate.
That is never possible so you still have to calculate with as much possible reserve.
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Old 02-09-2017, 05:30 PM   #35
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The BEST way to know EXACTLY what your tire pressure should be is to get your rig Smart Weighed. Escapees and RVSEF are two groups that provide this valuable service. Do it once, and your done (unless you make substantial changes).

https://www.google.com/search?q=Smar...RV+Smart+Weigh
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Old 02-12-2017, 01:55 PM   #36
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Originally Posted by LJS1211 View Post
Last week I purchased new E rated tires for my F150. Went with the BF Goodrich KO2 (275/65/18) and so far I'm very happy with them. These are larger than the tires that came from the factory (265/60/18). I'm pulling my trailer for the first time this weekend so had a quick question.

The tire shop originally put the PSI at 35 based on the door sticker but after reaching about to BF Goodrich they suggested to bump it up to 45 for everyday driving. They were not able to give any recommendations for tire pressure while pulling a trailer since there are so many variables like trailer size, weight and cargo. The tire shop suggested going to 50 pounds and then deflating back down after the trip. I'm just curious if others actually bump up their PSI while towing and have you noticed a difference in doing this? Just trying to figure out if there is a benefit to doing this. Thanks in advance for your feedback.
Some important information is missing.

1. We are talking about the tow vehicle tires - the F150
2. You didn't identify the OE tires as being P type or LT type. This makes a major difference. With a 35 psi door jam sticker number of 35 I suspect the OE tires are P type
3. It is the air pressure and not the tire construction that supports the load on a tire, so buying LR-E (80 psi) tires when you never run higher than 65 (LR-D) is a waste of money.
4. The door jam pressures are based on the car company making some estimates on how much and how often you have the vehicle empty or fully loaded. You might check the owners manual and see if they give an empty and loaded tire inflation suggestion
5.I suggest you get the F150 on some truck scales when empty and again when fully loaded with the trailer also fully loaded and learn the real facts of the various axle loads under both conditions.
6. Knowing the real loads you can use the tire Load & Inflation tables to learn the MINIMUM cold inflation pressure for the F150 for the two situations. I suggest you a margin of +10% of the table inflation
7. Trailer tires are completely different situation and should always be inflated to the tire sidewall inflation. You should also run no more than 85% of the trailer tire max load rating when on a scale. Cornering, sway and side wind loads have been shown to shift loads side to side by 10% or more. Also the Interply Shear on tires in trailer application needs to be considered as this is a major contributor to trailer tire belt separations.

Hope this info helps clarify
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Old 02-12-2017, 04:35 PM   #37
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Your number 3 is based on your opinion and not on any facts. The extra thickness of the tire may indeed not be waste of money if you pick up a screw and it would puncture a D, but not an E.

As for your number 4 the door jam pressure for the OEM tires on any car or truck will support the full GVWR. That is the whole point.

You left us hanging about what the major difference is on your number 2.
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Old 02-12-2017, 10:56 PM   #38
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Your number 3 is based on your opinion and not on any facts. The extra thickness of the tire may indeed not be waste of money if you pick up a screw and it would puncture a D, but not an E.

As for your number 4 the door jam pressure for the OEM tires on any car or truck will support the full GVWR. That is the whole point.

You left us hanging about what the major difference is on your number 2.
#3 is based on the fact that the Load Inflation tables only show a change in inflation as necessary to achieve a change load capacity.
Having designed LR-D and LR-E tires in a a line of tires I can assure you that not all LR-E tires had more tread or sidewall thickness than LR-D tires. If you choose to not believe me I can only suggest that you obtain a couple of tires from the same line and do a dissection.

#4 is correct except that some Pick-ups have two different suggested inflations and only the higher inflation number matches the GAWR.

#2 P type tires are primarily designed for passenger vehicle use. The design objectives usually focus on better ride and better fuel economy. You should also remember that when P type tires are applied to "Multi-purpose" vehicles and trailers the load capacity is to be "De-rated" by dividing by 1.10. Multi-purpose means station wagons, SUV, Pickups, vans and such. P type tires come in Standard and "Extra Load" with the Extra Load tires being rated to carry slightly higher inflation to support a little more load.

LT are Light Truck type usually come in LR-C, LR-D and LR-E but not all lines of LT tires have these three load ranges.
Since the load calculation formula is different for LT than it is for P type and LT tires are not De-rated as they are intended to be used on trucks and SUV
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Old 02-13-2017, 11:18 AM   #39
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Do you increase tire pressure when towing?

Point taken on #2 on derating P's.

Dodge HD pickups many years ago had two pressure ratings. Doesn't apply to half tons.

So you have two Goodyear Marathon ST tires 225/75R15 in D and E. You are saying that the tires are identical thickness? Seems counterintuitive.
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Old 02-13-2017, 12:38 PM   #40
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Point taken on #2 on derating P's.

Dodge HD pickups many years ago had two pressure ratings. Doesn't apply to half tons.

So you have two Goodyear Marathon ST tires 225/75R15 in D and E. You are saying that the tires are identical thickness? Seems counterintuitive.

First off it is important to not mix info and advice between different types of tires or different applications.
P, LT, ST & TBR ( 19.5 & 22.5 truck,bus radial with no letter prefix in the size.) The OP question was on the LT application.


But to answer your question on "thickness"

There are two different areas where different construction results in different Load Range for radial tires. The Belts and the bead.

There are a couple of different tests that a tire design must pass before it would go to production.

1. "Plunger" test. Here a 3/4" dia rod with a hemispherical head is slowly pressed on the center of the tread without going through. Different tires have different minimum specs given in in-Lbs. Not torque but the number of inches the rod deflects the tread and the pounds force applied. For example suppose a LR-D tire must resist 5000 in- lbs so the rod is pressed against the tire and the movement and force needed are recorded. 1" deflection with 5000 # force would pass. So would 2" deflection with 2500# force. The same size LR-E tire might have a spec of 6000 in-lbs.

I think you can see that there are a number of ways you might change the tire construction with sometimes even a "softer" construction (more inches) allowing the tire to meet the spec.
The above is a DOT regulation spec.

The other test is a burst test where we apply increased pressure and the tire must contain that pressure. One spec might be retaining 250% of the tire sidewall inflation. With this test sometimes the belts are the weak link, sometimes the sidewall and sometimes the steel hoop or bead that holds the tire on the wheel.

I worked on developing a LR-E when we already had a LR-D so I took the LR-D tire, ran the two tests and discovered the weak link was the bead. Once I increased the number of strands of wire in the bead the new tire meet the LR-E spec. In this case there was zero difference in the rest of the tire.

Some tires might need a stronger body, some stronger belt package and some as in this example a stronger bead package. Stronger belt might be accomplished with more strands of steel of the same size so there would be no additional thickness, so maybe you can see that tire thickness is not a good predictor of tire Load Range.
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