Is this my unicorn?

[ShagNasty]

Consumer Reports did a study in 2006 where they measured pressure loss of nitrogen-filled Vs air-filled tires over a one year period. They took 31 pairs of all season, automotive tires (H and V speed rated). One tire of each pair was filled to 30 psi with air, the other tire from the pair was filled to 30 psi with nitrogen. All 31 pairs were then set aside, outdoors for 12 months.



Their conclusion was that nitrogen does reduce tire pressure loss over time, but the reduction is only 1.3 psi.



Air-filled tires, originally filled to 30 psi lost 3.5 psi over a one year period.

Nitrogen-filled to the same starting pressure of 30 psi lost 2.2 psi over the same period.

More importantly ALL tires lost pressure, so consumers should check their tire pressures routinely regardless of the gas used.



The air around us, in our atmosphere, what we breathe and what is in most automotive tires is a mixture of gasses.

Air = 78% nitrogen + 20.95% oxygen + 1% other gasses ( 0.93% argon, 0.038% carbon dioxide, trace amounts of other gases and a variable amount of water vapor).

So, already all of the above claims are not true by 78% because going to pure nitrogen will only replace 22% of the tire’s internal volume.



The claims of improved steering, handling and braking, as well as reduced chances of tire failure and improved fuel economy are true for properly inflated tires regardless of the gas used to fill them.



Then there’s the claim regarding the reduction of internal tire oxidation because nitrogen is inert and oxygen is corrosive. I don’t think any of us have ever replaced a tire that had internal rubber decay because of oxygen corrosion. Although it is partly true –oxygen is corrosive-, your tires will wear out many times over before oxygen starts to damage the rubber material. If this claim were true and oxygen causes rubber corrosion that quickly, what about the outside of the tire? It is exposed to 22% oxygen even if you have pure nitrogen on the inside!



Some people also will tell you that tires filled with nitrogen don’t change pressure as much with heat as those filled with air, or that tires filled with nitrogen run cooler than those with air and that’s why most race cars including F1, Indy and NASCAR all use it.

Again, not true.

At the temperature (150 – 250ºF) and pressure (25 – 45 psi) thresholds found in racing tires, both air and nitrogen will act as “ideal gasses”, meaning that they will react exactly the same to temperature and pressure.
Oh, I almost forgot. There are those that claim that since nitrogen is lighter than air you’ll save weight and have better performance.



OK, so let’s analyze this one, I mean, less unsprung weight is good, no?



The weight difference between oxygen and nitrogen is less than 3%, but let’s take the full 3%.

One 255/40/17 summer tire holds approximately 13.88 liters (0.5 cu.ft.) of air at 2 bar (29.4 psi).

One liter of air is roughly equal to 1 gram so there are roughly 13.88 grams of air per tire, 55.52 grams in all 4 tires. Nitrogen is 3% lighter than oxygen, but there’s only 22% oxygen in air, so the difference in weight from all 4 tires is 0.3664 grams, that’s a whopping one third of a gram!

Here’s the math: 55.52 gr x 0.03 x 0.22 = 0.3664 gr

To put it in perspective, one official ping pong ball weighs 2.7 grams.



So, in essence, filling your tires with nitrogen won’t hurt anything and will provide some minimal benefits.



But, is it worth it?

Absolutely ... if you go to shops where it’s a free service with your new tires.

But paying an average of $10.00 per tire is absolutely not worth it.



Furthermore it may give you a false sense of security where you won’t regularly inspect your tires. Remember, even filled with pure nitrogen your tires will lose pressure over time.

[BennysTire]

Originally Posted by ShagNasty

Consumer Reports did a study in 2006 where they measured pressure loss of nitrogen-filled Vs air-filled tires over a one year period. They took 31 pairs of all season, automotive tires (H and V speed rated). One tire of each pair was filled to 30 psi with air, the other tire from the pair was filled to 30 psi with nitrogen. All 31 pairs were then set aside, outdoors for 12 months.



Their conclusion was that nitrogen does reduce tire pressure loss over time, but the reduction is only 1.3 psi.



Air-filled tires, originally filled to 30 psi lost 3.5 psi over a one year period.

Nitrogen-filled to the same starting pressure of 30 psi lost 2.2 psi over the same period.

More importantly ALL tires lost pressure, so consumers should check their tire pressures routinely regardless of the gas used.



The air around us, in our atmosphere, what we breathe and what is in most automotive tires is a mixture of gasses.

Air = 78% nitrogen + 20.95% oxygen + 1% other gasses ( 0.93% argon, 0.038% carbon dioxide, trace amounts of other gases and a variable amount of water vapor).

So, already all of the above claims are not true by 78% because going to pure nitrogen will only replace 22% of the tire’s internal volume.



The claims of improved steering, handling and braking, as well as reduced chances of tire failure and improved fuel economy are true for properly inflated tires regardless of the gas used to fill them.



Then there’s the claim regarding the reduction of internal tire oxidation because nitrogen is inert and oxygen is corrosive. I don’t think any of us have ever replaced a tire that had internal rubber decay because of oxygen corrosion. Although it is partly true –oxygen is corrosive-, your tires will wear out many times over before oxygen starts to damage the rubber material. If this claim were true and oxygen causes rubber corrosion that quickly, what about the outside of the tire? It is exposed to 22% oxygen even if you have pure nitrogen on the inside!



Some people also will tell you that tires filled with nitrogen don’t change pressure as much with heat as those filled with air, or that tires filled with nitrogen run cooler than those with air and that’s why most race cars including F1, Indy and NASCAR all use it.

Again, not true.

At the temperature (150 – 250ºF) and pressure (25 – 45 psi) thresholds found in racing tires, both air and nitrogen will act as “ideal gasses”, meaning that they will react exactly the same to temperature and pressure.
Oh, I almost forgot. There are those that claim that since nitrogen is lighter than air you’ll save weight and have better performance.



OK, so let’s analyze this one, I mean, less unsprung weight is good, no?



The weight difference between oxygen and nitrogen is less than 3%, but let’s take the full 3%.

One 255/40/17 summer tire holds approximately 13.88 liters (0.5 cu.ft.) of air at 2 bar (29.4 psi).

One liter of air is roughly equal to 1 gram so there are roughly 13.88 grams of air per tire, 55.52 grams in all 4 tires. Nitrogen is 3% lighter than oxygen, but there’s only 22% oxygen in air, so the difference in weight from all 4 tires is 0.3664 grams, that’s a whopping one third of a gram!

Here’s the math: 55.52 gr x 0.03 x 0.22 = 0.3664 gr

To put it in perspective, one official ping pong ball weighs 2.7 grams.



So, in essence, filling your tires with nitrogen won’t hurt anything and will provide some minimal benefits.



But, is it worth it?

Absolutely ... if you go to shops where it’s a free service with your new tires.

But paying an average of $10.00 per tire is absolutely not worth it.



Furthermore it may give you a false sense of security where you won’t regularly inspect your tires. Remember, even filled with pure nitrogen your tires will lose pressure over time.

I remember that Consumer Reports article. It left more questions than answers. Was the tire purged when nitrogen filled? Was tanked nitrogen used or oxygen filtered nitrogen used? Was the air from a 12v pump, shop air, service truck? Were the tires inflated in succession, individually? The nitrogen was measured to 95%, was the moisture level measured? Do the pressure readings account for the pressure lost from checking the pressure? Steel wheels or aluminum? Used wheels or brand new? Was the pressure checked with a dial guage, digital guage, pencil guage, TPMS sensor? Too many unknowns for this to be even remotely scientific...

Also, I question the math on the weight of air...

Good input however [emoji6]

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[Robin97396]

That's some intense tire information that's way over my head. I understand it but never considered all the variables in inflating a tire.

Not that I'd want to throw a wrench into the gearing here, but as a home brewer I'll likely be traveling with my CO2/nitrogen tank to pressurize my corny kegs. It's 20% nitrogen. If I'm stuck in the mountains with low tire pressure, is there any problem with using my gas mix? And yes I've got a compressor on the bus. I might want to inflate a tire that the bus can't park beside.

[BennysTire]

Originally Posted by Robin97396

That's some intense tire information that's way over my head. I understand it but never considered all the variables in inflating a tire.

Not that I'd want to throw a wrench into the gearing here, but as a home brewer I'll likely be traveling with my CO2/nitrogen tank to pressurize my corny kegs. It's 20% nitrogen. If I'm stuck in the mountains with low tire pressure, is there any problem with using my gas mix? And yes I've got a compressor on the bus. I might want to inflate a tire that the bus can't park beside.

You can fill a tire with just about any gas in a pinch, I'd avoid flammable ones[emoji57]

The pressurized gas, whatever it may be (air included) is only there to press on the inner walls of the tire to support the weight of the vehicle. Many pounds of pressure (On each square inch of the walls![emoji57])

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[Robin97396]

Good to know, thanks. I was thinking my gas mix would most likely get used for inflating motorcycle tires when to far away from my bus to use air.

The only flammable thing I've put in a tire was starting fluid. That cam get exciting on the really large tires.

[BennysTire]

Originally Posted by Robin97396

Good to know, thanks. I was thinking my gas mix would most likely get used for inflating motorcycle tires when to far away from my bus to use air.

The only flammable thing I've put in a tire was starting fluid. That cam get exciting on the really large tires.

I would use starting fluid as an absolute LAST resort. So technically, avoid at all costs. I could take it a step further and not even recommend airing up an unseated tire yourself without proper training... But I made that mistake in the YouTube comments section and it starts a never-ending barrage of "I know what I'm doing" and "What could go wrong" all the way to "yeah, that's what they say because their boss told them to say" and "just trying to make money" comments.

I've come to terms with the fact that I can't stop anyone from jumping off a bridge. But, if someone wants to know what's at the bottom without jumping, I'll gladly tell them...

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[Robin97396]

Well, sorry I haven't seen that one of your vids. Yes that's only as a last resort. There is reasonable potential for someone to loose a finger while lighting the starting fluid.

This was military with 8 ft tall tires, and yes problems seating them. It's more scarey with tires that big.

[BennysTire]

Originally Posted by Robin97396

Well, sorry I haven't seen that one of your vids. Yes that's only as a last resort. There is reasonable potential for someone to loose a finger while lighting the starting fluid.

This was military with 8 ft tall tires, and yes problems seating them. It's more scarey with tires that big.

You won't see that video from me. I simply commented on some 4wd adventure video where they were giving a crash course on getting out of the woods when you get a flat tire. There was so much wrong with it, so many dangerous situations that the untrained would put themselves in, my conscience wouldn't let me not comment...

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[Robin97396]

I'm just glad to be past the split ring rims. Those were fun rascals. Did some people use glue to seat the tire on the rims? I actually had to give up on breaking the bead away from the rim on certain rims.

So, where is next unicorn?

[cadillackid]

so how the heck do I tell whether I have hib pilot hubs, or stud pilot, or stud pilot wheels on huib pilot rims???

people here are saying navistar never used hub pilot on a school bus and my fingers look like those fingers mentioned as too weak to be hub pilot.. yet the nuts look more like hub pilot nuts..

will the accuride number tell me what it is?
I know they are darned 8 lug 19.5's which is a PITA as i wanted bigger wheels..

-Christopher

[BennysTire]

Originally Posted by cadillackid

so how the heck do I tell whether I have hib pilot hubs, or stud pilot, or stud pilot wheels on huib pilot rims???

people here are saying navistar never used hub pilot on a school bus and my fingers look like those fingers mentioned as too weak to be hub pilot.. yet the nuts look more like hub pilot nuts..

will the accuride number tell me what it is?
I know they are darned 8 lug 19.5's which is a PITA as i wanted bigger wheels..

-Christopher

-If you have no beveled hole on your wheels, they're likely hub piloted wheels.
-If your lug nuts have an attached flange washer that sits flat against the wheel, it's likely hub piloted nuts.
-If your studs accept the nuts, they're likely hub piloted studs (Budd has different size/thread)
-If your brake drum has holes similar in size to the studs, it is likely the drum for a hub piloted hub.
-If your hub holds the studs properly (not loose or welded on) then it is likely a hub piloted hub.

By design, the hub piloted setup and the stud piloted setup have components that are all dissimilar. This avoids the wrong combinations.
EXCEPT for the fact that you CAN put a stud pilot wheel on a hub pilot hub and screw the washer nuts on and "hide" the beveled hole underneath. Seen it done. Even saw it drive around... A LOT, before it was discovered/fixed.

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[Robin97396]

On a somewhat similar note to this discussion, kind of like a 4th cousin, I was wanting to ask your opinion on snow chains. Dual chains? Worth while or they just get us stuck in worse places? Steer tire chains too, or no?

I'm thinking single rear wrecker chains, not v-bar, and lighter diamond pattern steer tire chains for ice.

I know I should just stay home. That's no fun.

[BennysTire]

Originally Posted by Robin97396

On a somewhat similar note to this discussion, kind of like a 4th cousin, I was wanting to ask your opinion on snow chains. Dual chains? Worth while or they just get us stuck in worse places? Steer tire chains too, or no?

I'm thinking single rear wrecker chains, not v-bar, and lighter diamond pattern steer tire chains for ice.

I know I should just stay home. That's no fun.

Personally, I'm putting in OnSpot.
But single rear chains is all you need.
Chains up front (my opinion) would get you stuck in worse places. If you're in so deep your fronts aren't going where they should, park it.

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[Robin97396]

Sound advice, Thanks.

Even on my 6x6 duce and a half the front tires wouldn't steer unless it's nearly fully loaded. The front tires just slide when you turn them either way. I couldn't make it out my driveway in a 6x6 truck because I couldn't make the corner.

Yeah, I'm not as good at digging myself out anymore anyway. I've never had to be truck tire size chains before but thought it might be a good investment knowing how I am.

[jordan76]

Originally Posted by Robin97396

So, where is next unicorn?

This thread has taken on a life of its own, I almost hate to try to bring it back to my unicorn search. Lots of great information in here now though!

A handful of buses about an hour away came up for auction that check almost every one of my boxes, but are pretty high mileage/hours. What do you guys think about taking something on with over 350k miles and around 30k hours? These are pushers with Cummins 6CTA8.3 engines and MT643 transmissions, rear gear ratio of 4.44. They have basement storage, quite possibly a good amount were highway miles but that's hard to validate.

[Twigg]

Originally Posted by jordan76

This thread has taken on a life of its own, I almost hate to try to bring it back to my unicorn search. Lots of great information in here now though!

A handful of buses about an hour away came up for auction that check almost every one of my boxes, but are pretty high mileage/hours. What do you guys think about taking something on with over 350k miles and around 30k hours? These are pushers with Cummins 6CTA8.3 engines and MT643 transmissions, rear gear ratio of 4.44. They have basement storage, quite possibly a good amount were highway miles but that's hard to validate.

Awesome drive-train.

That engine might be getting close to rebuild time, but I love my 6CTA. On the other hand, it may go another 150k.

[Tango]

That is a sweet engine/tranny combo and CAN easily go a half million. But...only if it was well maintained. I'd have to pull and run oil samples on both before committing.

[Jdawgsfanasty]

Originally Posted by jordan76

This thread has taken on a life of its own, I almost hate to try to bring it back to my unicorn search. Lots of great information in here now though!

A handful of buses about an hour away came up for auction that check almost every one of my boxes, but are pretty high mileage/hours. What do you guys think about taking something on with over 350k miles and around 30k hours? These are pushers with Cummins 6CTA8.3 engines and MT643 transmissions, rear gear ratio of 4.44. They have basement storage, quite possibly a good amount were highway miles but that's hard to validate.

Diesels have a million miles in them if they are maintained...

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[jordan76]

Originally Posted by Tango

That is a sweet engine/tranny combo and CAN easily go a half million. But...only if it was well maintained. I'd have to pull and run oil samples on both before committing.

What's the turnaround time on those tests? Even if I could get down there tomorrow and convince them to let me take some samples, the auctions end on Fri, I'm guessing I couldn't get results that quick.

[Tango]

Best I've heard of was about a week. With Overnight shipping both ways.