10psi tire pressure makes a difference...

[Chaos Theory]

I've been running 35 inch Nitto Ridge Grapplers at 33-35 psi on my Mojave the last 5k miles. I had my tires rotated (and rebalanced) this weekend, and immediately noticed the guy jacked my psi up to 45, which apparently is "recommended" for an LT tire. I figured it would feel like I was driving on basketballs, but let it go for experimental reasons.

I've since driven 150 or so miles and noticed the following:

1) 1.5 MPG increase. I understand the concept of rolling resistance, but was surprised to notice that much change with only 10psi added. When you're only getting 16-17 anyway, that's nothing to scoff at. It's like adding another gallon of gas to each tank.

2) I feel more of the road imperfections in my steering wheel, but no additional wandering, which was my concern. Mojave suspension helps, but I also have a 1.5 inch spacer on the front, due to my steel bumper/winch. I also had adjustable LCAs and camber dialed in when I added the spacer/bigger tires initially, but figured there'd be more downsides to higher pressures.

So I realize it's all personal preference, but what is your tolerance for road rumble vs increased MPG?

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[ZeeJay]

The truck I keep around 37 ish, believe that’s what the all “important” tire data tag tells me. Really that only because it still has the BFG MTs it came with so just let that sleeping dog lay.
My ZJ on a lift that’s another story. Ideally it handles like a fine car at 35ish, smooth as butter even with nothing OEM holding it up or steering it anymore but…..I keep the Cooper STT’s up at 50. Handles like ass, drifts around, smash a mouse….feel it. 15 pounds makes that 4.0 feel like it gained 20 HP and about 1.5 extra in fuel slurping. Which I’ll take because it gets 13.5 now, I’m totally on board with 15. It will wreck the tires I’m sure but so be it, the god awful fuel burn could probably by 2 sets every year.

 

[bd100]

I have LT-E tires wear perfectly fine for the life of the tire at 50 PSI, which I use for towing at highway speed in the heat of summer. They were getting too hot at 40 PSI, which you could tell by comparing front and back tire sidewalls by touch.

But I leave them at 50 PSI all the time anyhow, for the improved handling. Note that these are stock-ish sized tires, not 35s or whatever, which would take less pressure.

The manual for the older pickup has a chart showing inflation pressures per type of tire, and says to add X for highway in summer and Y for towing. It came to 50 PSI for the LT-E tires.

 

[PuddleJumper]

I've been running 35 inch Nitto Ridge Grapplers at 33-35 psi on my Mojave the last 5k miles. I had my tires rotated (and rebalanced) this weekend, and immediately noticed the guy jacked my psi up to 45, which apparently is "recommended" for an LT tire. I figured it would feel like I was driving on basketballs, but let it go for experimental reasons.

I've since driven 150 or so miles and noticed the following:

1) 1.5 MPG increase. I understand the concept of rolling resistance, but was surprised to notice that much change with only 10psi added. When you're only getting 16-17 anyway, that's nothing to scoff at. It's like adding another gallon of gas to each tank.

2) I feel more of the road imperfections in my steering wheel, but no additional wandering, which was my concern. Mojave suspension helps, but I also have a 1.5 inch spacer on the front, due to my steel bumper/winch. I also had adjustable LCAs and camber dialed in when I added the spacer/bigger tires initially, but figured there'd be more downsides to higher pressures.

So I realize it's all personal preference, but what is your tolerance for road rumble vs increased MPG?

Hit the head on the nail. I run 35 for daily use/ comfort. 40 front, 42 rear for towing. Basically I alter pressure based on what I'm doing and what experience tells me will be most desirable. Also keep in mind as your tire heats up the pressure will go up. the rang at which it does is usually based on the combo your running. My setup gains about 6 psi with heat.

 

[Zachanadandy]

My experience differs significantly from yours. I see no difference in mpg running 30psi or 40psi after the tire rotation techs over inflate the tires. Now granted I run a 37x12.50r17 E rated kanati mud hog so the side walls are stiff. The ride difference between 30 and 40 psi is significant. I'd rather drive around at 20psi (which I have after wheeling) than at 40psi personally, but you do you.

 

[PuddleJumper]

My experience differs significantly from yours. I see no difference in mpg running 30psi or 40psi after the tire rotation techs over inflate the tires. Now granted I run a 37x12.50r17 E rated kanati mud hog so the side walls are stiff. The ride difference between 30 and 40 psi is significant. I'd rather drive around at 20psi (which I have after wheeling) than at 40psi personally, but you do you.

Depending on how heavy your run you truck. you could probably run 10-15 psi on those and wouldn't notice. e rated 37s can hold some shit.

 

[Zachanadandy]

Depending on how heavy your run you truck. you could probably run 10-15 psi on those and wouldn't notice. e rated 37s can hold some shit.

They feel warm after driving on the freeway at 20 psi but otherwise seem unfazed.

 

[Rahkmalla]

They feel warm after driving on the freeway at 20 psi but otherwise seem unfazed.

heat=wear. warmer tires become more pliable, which increases grip, but also means they wear faster.

1.5 MPG increase.

Maybe i'm just being a doubting thomas, but I find it hard to believe you can run 50psi without affect the tire's footprint. A narrow footprint would improve MPGs... but also make your tires wear unevenly. I don't feel like doing the math, but top of head it feels like you'd need a lot more than a 10% MPG increase to overcome the costs of wearing out the center of your tread faster.

 

[Zachanadandy]

heat=wear. warmer tires become more pliable, which increases grip, but also means they wear faster.

Maybe i'm just being a doubting thomas, but I find it hard to believe you can run 50psi without affect the tire's footprint. A narrow footprint would improve MPGs... but also make your tires wear unevenly. I don't feel like doing the math, but top of head it feels like you'd need a lot more than a 10% MPG increase to overcome the costs of wearing out the center of your tread faster.

I think heat wear is an overrated concept unless you're running 10-15psi on the street. We were in moab, brand new Yokohama 37" x-mts on our heavy JLUR. Aired down to 17psi and wheeled it/drove it all over the area highways at speed for the next 5 days. Leaving town in the early morning to head home and I had forgotten my air compressor at the house. We tried 3 different gas stations and all had compressors out of service. Started the 1100 mile drive home with the cruise control set at 85mph. With the heat tires settled at 20-21psi. Every time we stopped for gas, same story, either a broken compressor or someone parked in the way. Ended up driving all 1100 miles aired down. After the 1st couple 5 tire rotations there was no visible difference in the tires including the one that didn't take the hard use in moab and "heat wear" ride home. Tires had 40k+ miles on them when replaced and still had some good tread left... from an extreme mud terrain tire. So much for another forum paranoia in my opinion.. I don't worry in the slightest about hopping on the highway between trails any more.

 

[Wheelin98TJ]

heat=wear. warmer tires become more pliable, which increases grip, but also means they wear faster.

Maybe i'm just being a doubting thomas, but I find it hard to believe you can run 50psi without affect the tire's footprint. A narrow footprint would improve MPGs... but also make your tires wear unevenly. I don't feel like doing the math, but top of head it feels like you'd need a lot more than a 10% MPG increase to overcome the costs of wearing out the center of your tread faster.

If you increase MPG from 16 to 17.5 and gas is $3.50/gal, your cost of gas per mile goes from $0.21875 to $0.2058. A savings of $0.01295/mile.

If this makes your 50k mile tires 30k mile tires and the tires cost $1,500, the cost per mile for tires goes from $0.03 to $0.05. An additional cost of $0.02/mile.

Just throwing some random #s out to see how it calculates out. Obviously if gas is more expensive, tires are cheaper, and the wear impact is not 20k miles, the #s will come out quite different.

 

[Chaos Theory]

I guess, to clarify... Nitto's I run, an LT "E" tire, are designed to have 45 psi, per the sidewall. The majority of us are running them lower, simply based on road comfort.

So any additional wear and tear comes from under-inflating, not recommended specs.

 

[PsyRN]

I run the 35" E-rated Ridge Grapplers around 37psi cold when it's about 60F outside at sea level with nothing in the camper. I've seen them drop to 32 when colder and when I was fully loaded and driving in Death Valley when it's 128F, they went up to 42-44psi. I notice they do run a bit smoother when at higher psi, but almost too smooth. I don't think I would run them over 40psi on the daily.

 

[Wheelin98TJ]

I guess, to clarify... Nitto's I run, an LT "E" tire, are designed to have 45 psi, per the sidewall. The majority of us are running them lower, simply based on road comfort.

So any additional wear and tear comes from under-inflating, not recommended specs.

It's not 45 PSI for all applications. That is for a certain load which is higher than the load you're carrying.

 

[Rahkmalla]

I guess, to clarify... Nitto's I run, an LT "E" tire, are designed to have 45 psi, per the sidewall. The majority of us are running them lower, simply based on road comfort.

The sidewall is the maximum, not what's recommended or what the tire is "designed" to be set at. And 45 psi cold is not 45psi on the highway, which means if you're running a tire that says 45psi on the sidewall at 45psi cold, you're running 46-47 on the highway and therefore exceeding your tire's maximum rated pressure. That's not a good idea.

and PSI recommendations from mnfrs aren't solely for road comfort. they are also for even tire wear. you can save all kinds of MPGs by having a 4 inch wide contact patch on a 12.5 inch wide tire... except now you're asking 1/3 of your tire to handle the load that the who thing is supposed to handle.

 

[Flanders]

I've been running 35 inch Nitto Ridge Grapplers at 33-35 psi on my Mojave the last 5k miles. I had my tires rotated (and rebalanced) this weekend, and immediately noticed the guy jacked my psi up to 45, which apparently is "recommended" for an LT tire.

The TRA Load Inflation Tables show around 35 psi for this application. Does the tire manufacturer recommend something different?

The sidewall is the maximum, not what's recommended or what the tire is "designed" to be set at. And 45 psi cold is not 45psi on the highway, which means if you're running a tire that says 45psi on the sidewall at 45psi cold, you're running 46-47 on the highway and therefore exceeding your tire's maximum rated pressure. That's not a good idea.

The OP's tires are rated for 80 psi cold. According to TRA, the cold inflation pressure is “taken with the tires at the prevailing atmospheric temperatures and do not include any inflation pressure build-up due to vehicle operation.”

If you increase MPG from 16 to 17.5 and gas is $3.50/gal, your cost of gas per mile goes from $0.21875 to $0.2058. A savings of $0.01295/mile.

If this makes your 50k mile tires 30k mile tires and the tires cost $1,500, the cost per mile for tires goes from $0.03 to $0.05. An additional cost of $0.02/mile.

Just throwing some random #s out to see how it calculates out. Obviously if gas is more expensive, tires are cheaper, and the wear impact is not 20k miles, the #s will come out quite different.

I seriously doubt that running them at 45 psi is going to reduce the tread life by 40%, or even half that. I've run the tires on my other pickup about 5 psi over the placard number for years and never seen any sign of excess wear along the middle of the tread, which is what you'd expect if you didn't know better.

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