Proper PSI for unloaded truck with range E tires?

[football]

I agree with you wwilson. Tires are meant to filled and checked at cold temp. That means the pressure should be 50 PSI (or whatever) when cold. In the morning. They obviously account for daily temp rises and pressure increases from driving friction.

If your call calls for 50 PSI, that’s how much pressure should be in your tires at 700am in the morning when the tires are at their coldest.

 

[JHZR2]

Yes, I see pressure increases like this almost every time to tow the 5th wheel. The tires are made to handle the expansion. Said a different way, the tire engineers expect pressure increases during operation and design the tire load carrying capacity with the expansion, so if you try to outsmart the engineers by lowering your cold pressure so that at operating temperature the tires don't exceed max sidewall pressure, all you have done is lowered your tire carrying capacity. You have done nothing to 'save' your tires from over inflation, because they are supposed to be 'over inflated' at operating temperature.

When heavily loaded, and I have loaded my trucks to max payload quite a bit, I’ll air up. But there are other cases where it’s just not the situation. And I suspect that it’s a better ride and maybe better wear characteristics if aired down. Especially the rears at 80 vs. something that may have a flatter contact patch.

 

[wwillson]

When heavily loaded, and I have loaded my trucks to max payload quite a bit, I’ll air up. But there are other cases where it’s just not the situation. And I suspect that it’s a better ride and maybe better wear characteristics if aired down. Especially the rears at 80 vs. something that may have a flatter contact patch.

Very true and you can look up the recommended tire pressure on the manufacturer's load chart. I drive the truck so rarely unloaded that I don't bother to decrease the pressure when unloaded.

 

[JHZR2]

Very true and you can look up the recommended tire pressure on the manufacturer's load chart. I drive the truck so rarely unloaded that I don't bother to decrease the pressure when unloaded.

Bht thats my point, what chart? Is the one at tire pressure.org good enough? Is some percentage above practical loaded weight good enough?

 

[burbguy82]

@JHZR2

A simple explanation:

The tire psi on your door, represent the PSI required for the vehicle to be loaded at max weight, which is why the rear PSI is 80. The front at 65. 80 at rear is because most of the weight under load is added to the rear, like when hauling stuff or trailering, of course.

Since the front does not change much, under most any condition, I would run a minimum of 65 in the front. With that being said, 65 in the rear would be more than sufficient under no or "lighter loads".

I am not the resident tire expert, but I have had a bunch of experience with tires and heavier trucks, on the user end and purchasing end. On my dually, I run 70 PSI on all the tires, under all load conditions, and get "good mileage" out of a set=45-50k. A duallys sometimes eat tires.

I can tell by the tag that your is a SRW.

Recently, I bought a M1008, it is a SRW, 1 1\4 ton truck, with 235 85 16 tires, roughly 31'' E load range. The previous owner, had said that there was a noticable vibration, at 50mph. I agreed. Looked at the tire pressure, and it was at 35. I pumped them up to 65, and the vibration went away, and rides smooth, and not just for a 38 year old truck.

There is something about E load range tires that really requires higher PSI at speed. I suppose it is just the increased mass of the tires, require more air for be supported while spinning.

A similar situation happened with my new to me, 09 LX570. The previous owner did the same thing, for "off road purpose" (aint no off roading in a mall parking lot)....anyway, same thing, 35 psi. These I pumped up to 50, and boom smooth as glass.

Anyway, tire pressure is important, and I hope this helps.

 

[KBEricR]

I have a set of Firestone Transforce 265-70R18 E rated tires on my 2018 Nissan Titan SV, door sticker says run tires at 35, I put these up to 50 and currently am sitting at 46,000 total miles on the set and 7/32nds with well over 25K miles towing a 6,000lb trailer. At 35 psi real hard to get 20mpg. With higher inflation frequently see 22-23 mpg, with all time high 26.4. Tires rated for 80psi.

 

[Skippy722]

I’m running 45psi front and rear in my ram with 10 ply tires. It’s still comfortable, they wear evenly, and it still handles good.

 

[JHZR2]

@JHZR2

A simple explanation:

The tire psi on your door, represent the PSI required for the vehicle to be loaded at max weight, which is why the rear PSI is 80. The front at 65. 80 at rear is because most of the weight under load is added to the rear, like when hauling stuff or trailering, of course.

Since the front does not change much, under most any condition, I would run a minimum of 65 in the front. With that being said, 65 in the rear would be more than sufficient under no or "lighter loads".

I am not the resident tire expert, but I have had a bunch of experience with tires and heavier trucks, on the user end and purchasing end. On my dually, I run 70 PSI on all the tires, under all load conditions, and get "good mileage" out of a set=45-50k. A duallys sometimes eat tires.

I can tell by the tag that your is a SRW.

Recently, I bought a M1008, it is a SRW, 1 1\4 ton truck, with 235 85 16 tires, roughly 31'' E load range. The previous owner, had said that there was a noticable vibration, at 50mph. I agreed. Looked at the tire pressure, and it was at 35. I pumped them up to 65, and the vibration went away, and rides smooth, and not just for a 38 year old truck.

There is something about E load range tires that really requires higher PSI at speed. I suppose it is just the increased mass of the tires, require more air for be supported while spinning.

A similar situation happened with my new to me, 09 LX570. The previous owner did the same thing, for "off road purpose" (aint no off roading in a mall parking lot)....anyway, same thing, 35 psi. These I pumped up to 50, and boom smooth as glass.

Anyway, tire pressure is important, and I hope this helps.

The fact that the mass doesn’t change much in the front axle makes a lot of sense, and that it will be heavier with a diesel is a good consideration too.

I generally run my car tires at or above door labels. Mercedes gives guidance on how much to over pressure the tires.

80 just seems so high for an unloaded truck bed…

I think I’ll take your approach of 65 all around. Makes sense.

Thanks!

 

[userfriendly]

Expansion is unreal under load & at highway speeds-the Transit dash indicated PSI goes from 85 cold to over 100!

Maybe you should try running G rated 19.5s on that critter.

 

[Big E]

I was getting uneven (center) tread wear on my truck running 50+ psi empty. The tire shop I used at the time recommended running 45 psi when empty.

Experimenting myself, I found that 45 to 48 was giving me good contact across the width of the tread, and solved the uneven tread wear issue.

I eventually switched to 265/75/16s which looked much better and solved my +2mph speedometer error.

My current '16 2500 Diesel gets 50psi in the rear when empty, which seems to work well.

 

[JHZR2]

I eventually switched to 265/75/16s which looked much better and solved my +2mph speedometer error.

My 96 4WD has that same size and I just realized that too - spot on speedometer with the larger size.

 

[JWC86]

My suggestion is to not over think this.

Try 40 rear, 50 front and chalk test. Go from there.

 

[CapriRacer]

First, those charts everyone is mentioning are MINIMUMS, not recommendations. Folks need to stay ABOVE that!

Second a 1996 is BEFORE the big Firestone/Ford controversy, and since that time, the car manufacturers have changed the way they do the specified inflation pressures - and in this case, it's the rear pressure. The photos shows the GAWR equal to the max load for the pressure. They don't do that nowadays. They currently specify about 15% more. We should, too!

The car manufacturers always test at the pressures specified - both fully loaded and empty. They will also test at any pressure they list in the owners manual. We should, too! But testing tires will destroy a set, so no one is going to do that!

And lastly, evenness of tire wear isn't as closely tied to pressure as everyone thinks. There are factors that have a stronger influence!

Specifically, that steer tires tend to wear in the shoulders and drive tires tend to wear in the center. That's one of the reasons many people think over inflation causes wear issues. It's also one of the reasons why tire rotation works to get longer life out of a set.

So what to do?

First, be careful - both in how far you go, but also be sensitive to how the vehicle feels. Back off at the first sign that there is any instability. I would hate for there to be any injuries just because someone overdid it.

There is a way to tell if you've gone too far - the Pressure Build-up Test: Barry's Tire Tech: Pressure This means dedicating some time, but I have confidence in the result.

 

[thastinger]

I’m running 45psi front and rear in my ram with 10 ply tires. It’s still comfortable, they wear evenly, and it still handles good.

I run 44 all around when unloaded and experience the same.

 

[JWC86]

First, those charts everyone is mentioning are MINIMUMS, not recommendations. Folks need to stay ABOVE that!

Second a 1996 is BEFORE the big Firestone/Ford controversy, and since that time, the car manufacturers have changed the way they do the specified inflation pressures - and in this case, it's the rear pressure. The photos shows the GAWR equal to the max load for the pressure. They don't do that nowadays. They currently specify about 15% more. We should, too!

The car manufacturers always test at the pressures specified - both fully loaded and empty. They will also test at any pressure they list in the owners manual. We should, too! But testing tires will destroy a set, so no one is going to do that!

And lastly, evenness of tire wear isn't as closely tied to pressure as everyone thinks. There are factors that have a stronger influence!

Specifically, that steer tires tend to wear in the shoulders and drive tires tend to wear in the center. That's one of the reasons many people think over inflation causes wear issues. It's also one of the reasons why tire rotation works to get longer life out of a set.

So what to do?

First, be careful - both in how far you go, but also be sensitive to how the vehicle feels. Back off at the first sign that there is any instability. I would hate for there to be any injuries just because someone overdid it.

There is a way to tell if you've gone too far - the Pressure Build-up Test: Barry's Tire Tech: Pressure This means dedicating some time, but I have confidence in the result.

Interesting idea for a test and easy to do for those of us that have vehicles equipped with tire pressure monitoring systems.

 

[BrendanC]

i’ve always run my E/F load tires at 65 PSI all the way around on my 3/4 ton. nice even wear and they don’t get hot.

 

[JHZR2]

First, those charts everyone is mentioning are MINIMUMS, not recommendations. Folks need to stay ABOVE that!

Second a 1996 is BEFORE the big Firestone/Ford controversy, and since that time, the car manufacturers have changed the way they do the specified inflation pressures - and in this case, it's the rear pressure. The photos shows the GAWR equal to the max load for the pressure. They don't do that nowadays. They currently specify about 15% more. We should, too!

The car manufacturers always test at the pressures specified - both fully loaded and empty. They will also test at any pressure they list in the owners manual. We should, too! But testing tires will destroy a set, so no one is going to do that!

And lastly, evenness of tire wear isn't as closely tied to pressure as everyone thinks. There are factors that have a stronger influence!

Specifically, that steer tires tend to wear in the shoulders and drive tires tend to wear in the center. That's one of the reasons many people think over inflation causes wear issues. It's also one of the reasons why tire rotation works to get longer life out of a set.

So what to do?

First, be careful - both in how far you go, but also be sensitive to how the vehicle feels. Back off at the first sign that there is any instability. I would hate for there to be any injuries just because someone overdid it.

There is a way to tell if you've gone too far - the Pressure Build-up Test: Barry's Tire Tech: Pressure This means dedicating some time, but I have confidence in the result.

This is great info, thanks.

The thing with the charts is that it almost looks like I could run 35-40 psi for an unloaded truck. Even as a minimum that seems too low.

I like the pressure rise test concept. When I’m going to use the truck for a good distance I’ll plan to try that.

 

[johnmyster]

Max inflation pressure for a LR-E tire is, by definition, 80 psi.

I second the motion for 55 psi, all around, unless this is something like a diesel that is especially heavy on the front axle. You could go 50 psi on the rear, but 55 gives you some margin in the event you need to do some unexpected load hauling, trailer towing, cold weather, leakdown, etc. Your back axle is probably 3000-3200 empty, so 55 psi gives you a good bit of load hauling margin.

60/55 (f/r) cold is what I ran on our last diesel crew cab pickup in the winter, when I suspected little chance of a trailer tow popping up...in a pretty similar size to the OP's scenario.

The thing with the charts is that it almost looks like I could run 35-40 psi for an unloaded truck. Even as a minimum that seems too low.

Keep in mind the charts are based on a minimum appropriate pressure for a given load. Not necessarily the ideal...the minimum.

 

[football]

My suggestion is to not over think this.

Try 40 rear, 50 front and chalk test. Go from there.

Well maybe he should “over think” this because your suggestion is dangerously low and blowout territory for load range E tires.

 

[Skippy722]

Well maybe he should “over think” this because your suggestion is dangerously low and blowout territory for load range E tires.

Granted on a half ton, but my truck calls for 40psi-43psi regardless of P metric or E, and that’s on a ~5,300lb truck. And like he said, if he’s going to be hauling heavy or towing he will air them up. He won’t be in blowout territory just driving it around at 40 rear/50 front at all.