05 Tacoma Tire pressure

You got it backward. Why would anyone ride around with 51 pounds of air pressure in a 3000 lb vehicle? That rating is the MAXIMUM allowable for the tire. Not what is recommended for daily use. If you ran that high pressure, you would be bouncing all over the road (and wearing your tires out very fast). Put the maximum tire pressure in your spare since (hopefully) it will just hang there for years before you need it. At least you'll have a longer time before all the air leaks out from time (which it will do....)

Max tire pressure is listed so that if you're towing something or hauling a load you can air up the tires. Look at the load ratings on the tires and it will say was the max carrying capacity is and at what pressure the tire needs to be to hold that capacity.

It is annoying that many places that install tires as well as oil change places that check levels and tire pressures seem to routinely fill the tires to the max level on the tire rather than see what the manufacture's recommendations are.

Car makers base their recommendations on comfort as much as anything else, but those recommendations seem to be disconnected from the reality of safety, performance and tire wear. After hydroplaning for 100 feet or so in my Tercel many years ago, I decided it was time to speak directly to the tire company (Michelin, in that case). I've done this every time I've bought new tires since them, and in every case, they've suggested a higher pressure.

While this sounds arbitrary, my mechanic has pointed out very slight issues with tread wear, so with every set of tires, we've made adjustments. I'm currently using Nokian WR tires, 265-70R16. Based on the aforementioned tire wear issues, as well as trial & error in snow & very wet roads, we've settled on 38 lbs cold pressure as optimum.

If I recall, my 2002 Tacoma came with BF Goodrich off road tires, which were hideous in snow. No amount of fiddling seemed to help. But, observing tread wear led us to use 32 as a starting point. I experimented as high as 38, and then gave up on them.

After 25 years and six cars in the family, I've never found a tire that performed optimally below 30 lbs, so I'd recommend that you begin at 32, work your way up to no more than the high 30s, and pay close attention to handling and wear.

You said - "After hydroplaning for 100 feet or so in my Tercel many years ago, I decided it was time to speak directly to the tire company (Michelin, in that case)." By "tire company" do you mean Michelin the Tire Company, or the tire store where you purchased your Michelin tires? On their website, Michelin the Tire Company clearly says "Always inflate your tires to the recommended pressure listed by your vehicle's manufacturer. This information can be found in the owner's manual and often on a placard located in the vehicle's door jamb, inside the fuel hatch, or on the glove compartment door." This copied from

. Ed

I called the company directly. The tires *were* inflated according to Toyota's specs, and were brand new. I'd already been driving for 15 years at that point, and had never experienced hydroplaning like that before. So, I knew something was wrong in a big way. The person I spoke to pretty much brushed off the manufacturer's pressure ratings, and had me raise it into the mid-30s. Never had a problem again.

I would've consulted the tire dealer, but I figured that if they set the tires at the lower pressure, they probably weren't very well informed. Afterward, I found a real mechanic, and he's NEVER set up any of my tires according to the car mfs specs.

In many cases, higher tire pressure reduces rolling resistance and saves gas. The value of the gas saved exceeds the value lost by increased tire wear in the middle of the tread.

Ken

Tread wear becomes a non-issue if you can get your hands on a Treadular Obsessometer. Damned if I can't find the link to the manufacturer, though. I'll keep looking.

A higher pressure can also decrease traction, as it lessens the tire's ability to conform to road contours.

Well, "too high" would do that. Somewhere, there's a happy medium for any car & tire combination. The problem is that people are led to believe they can take the car maker's advice at face value. You can't. In the case of my old Toyota, the recommended pressure was downright dangerous.

At the shop I used to work at, I was told to fill tires to 32lbs. Pretty much no exceptions. I never even looked at manufactures' specs or sidewalls. We dealt almost exclusively with Toyotas, Hondas, and Subarus, leaning waaay to the sedan side. Saw only a couple 4 Runners, no Tacomas/Pickups, and maybe one Forrester.

For optimum tire wear, wheel life and gas mileage, find a shop which has a nitrogen inflation system(most dealerships already have this). The molecular structure of nitrogen is several times larger than that of air used in conventional inflation systems. Since the rubber in tires and valve stems is permeable, regular air slowly escapes through the rubber itself. Since nitrogen molecules are so much larger, they are far less likely to leak through the rubber, maintaining a more stable pressure in ALL tires. Another benefeit of nitrogen is that it has far less water content than standard air, meaning nitrogen is inert and will not cause long term corrosion or pitting of the inside of your wheel or tires. Another benefeit of nitrogen...it is stable at high temperatures; it does not expand when heated or contract when cooled, this results in a CONSTANT air pressure inside your tires, whether they are hot from driving or cold from sitting. Regular air expands as you drive creating more pressure in your tires, reducing as your car sits and the tires cool.

Interesting idea, but this would mean switching mechanics. Not an option, at least until the current guys die or retire. :-)

Hoo boy, we've got ourselves a Nitrogen Generator System salesman working here! Let's break down the high-pressure ;-0 sales pitch...

Hello! The air we are breathing right now is roughly 78% nitrogen already, 21% oxygen, and the rest is trace gases. Oh, and a varying volume of water molecules as humidity. The nitrogen inflation systems can shunt the oxygen out of the gas stream and boost the output gas to fairly pure nitrogen the 98% - 99% range. This will slow down permeation leaks in your tires, but not eliminate them.

It's only dry if they take special care in the nitrogen generation gear at the tire shop to get all the moisture out of the finished product. The only sure way to eliminate the problem is if you spend a lot extra to buy "Dry Nitrogen" from an industrial gases supplier in high-pressure (3,000 PSI) cylinders.

The tire shop nitrogen generator machine that almost all shops use starts out with regular compressed atmospheric air from the station's regular air compressor, and moisture can get through the system unless they are very careful at each step to get it dried and keep it dry.

It DOES expand, it just expands /less/ - remember that "Air is composed of 78% Nitrogen" stuff above? Not a lot of difference, doesn't really affect anything, but it is a measurable phenomenon.

Nitrogen in tires got it's start in aviation, where they fill airplane tires to 200 PSI or more with Dry Nitrogen from a high- pressure cylinder. They have air compressors, but most single stage units top out at 125 PSI, and two-stage at 150 or 170 PSI. The cylinder makes it a whole lot more convenient and portable - use it anywhere, no power source required, just a pressure regulator.

Besides the other slight advantages mentioned above they used it for fire prevention - if your wheel or tire is on fire, or the plane is on fire with the wheel retracted into it's wheelwell, you don't want the tire to blow and add oxygen to the fire.

And with no available oxygen inside the tire, nitrogen inflation stops the oxidation deterioration of the inside air-sealing butyl rubber of the tire liner layer or inner tube. For large airplane tires that cost thousands of dollars each to buy and change it's an issue, for car tires...

It's a good thing to use it in your car tires, but not having Nitrogen equipment alone is not a good reason to switch shops.

-->--

Puuuullleeezzee!

The main benefit is simply that the nitrogen is pure and dry, creating a more predictable change in pressure throughout a tire's range of operating temperature. This is beneficial when tuning a race car, but of questionable value on the street. Daily driver cars driven within the law don't have their tires subjected to the temperature range seen by a race car.

A bit of water typically gets into the tire during the mounting process when the beads are lubed!

If nitrogen inflation is free, it can't hurt anything. Spending extra money for the service or seeking out a shop specifically for nitrogen inflation is a waste. This is pure marketing BS, with extra fuel provided by pit reports during NASCAR races.

"MrFixit469" sez:

I 'spose if one was to use helium, they'd get better gas mileage because their vehicle was lighter because of the buoyancy effect?

Good incredulity to ya, VLJ

You said ->"The molecular structure of nitrogen is several times larger than that of air used in conventional inflation systems."

This is BS. "air used in conventional inflation systems" is already 80% nitrogen. Most of the rest is oxygen which has a similar molecular size. I've seen it claimed that Nitrogen migrates through rubber at a much lower rate than oxygen (1/3 the rate????). However, I don't think miagration through the rubber is a major problem for either. Most air, or nitrogen leaks out through the valve or past the bead, not through the rubber.

You said -> "Another benefeit of nitrogen is that it has far less water content than standard air, meaning nitrogen is inert and will not cause long term corrosion or pitting of the inside of your wheel or tires."

It is not the water that corrodes your tires, it is the oxygen. The water does act like a catalyst, but the amount of water in "air" is trivial in a typical tire as far as promoting corrosion is concerned. Be honest now, when was the last time you had a problem with pitting on the inside of a wheel? For me it is never.

You said -> "Another benefeit of nitrogen...it is stable at high temperatures; it does not expand when heated or contract when cooled, this results in a CONSTANT air pressure inside your tires, whether they are hot from driving or cold from sitting. Regular air expands as you drive creating more pressure in your tires, reducing as your car sits and the tires cool."

This is total BS. First of all air is 80% Nitrogen. But more importantly, dry air and pure nitrogen have almost exactly the same pressure vs. temperature relationship at typical automotive tire pressures. If you have a lot of moisture in the air, it can afffect the relationship somewhat, but not enough that you would notice. Most commerical compressors do a fair job of removing moisture from air, so the difference between shop air and nitrogen is trivial for typical automobiles and light trucks.

Racers use nitrogen to avoid having moisture in the tires. Becasue of the high speeds and high cornering loads, the tires on race cars get very hot. Optimum handling depends on minute changes in air pressure. The pressure increases as the tire heats up. The pressure build-up as the tire heats up is slightly more predcitible with pure nitrogen than with "local" air becasue the moisture content of "local" air can vary depending on the conditions when the tires were filled. We are talking about tiny differences (not even 1/2 lb of pressure). There is no chance the typical driver is going to know the difference.

The only advantage I am willing to conceede is that pure nitrogen will help preserve the inside of the tire carcass longer than normal air. The O2 in air will react with the carcass and degrade it over time. However, "over time" is 10 years or more. For most of us, this is not going to matter at all. For large fleets that recap tires, it might matter, escpecially if they maintain their own nitrogen system. However, if you are paying someone to fill your tires with Nitrogen, I think you are making a terrible economic decision.

Now for the killer point - most tire stores that inflate tires with "nitrogen" aren't using pure bottled nitrogen, they are using a commercial nitrogen generator. These don't actually provide "pure" nitrogen. They remove O2 and water vapor from the air and provide something close to 95% nitrogen (when properly maintained). So you are paying to go from around 80% nitrogen to 95% nitrogen. Plus - when the tire is mounted, it's volume is filled with plain old air. This mean's that about 25% of the gas in the tire after it is inflated to pressure is the plain old air that was in the tire when it was first mounted. So after the tire is finally filled to its working pressure, approximately

20% of 25% of the air that was in the tire after mounting (but before pressurization) is oxygen plus another 5% of 75% of "nitrogen" added to pressurize the tire - so 5% to 10% of the gas in the tire is still oxygen. So in the end, you are paying to go from a gas containing 20% oxygen to one conating around 8% oxygen. I can't imagine this is worthwhile - except to the people selling the service. Plaus what ahppens when you add air to the tire to compensate for leaking, or temperature changes? After a couple of years, what do you suppose the composition of the air in the tire will be?

I don't suppose this can be called an obvious scam, but you should check out the source of most of the "positive" talk about nitrogen for automotive tires. Mostly it comes from stores selling nitorgen for tires, companies than manufacturer the nitrogen generators, and tire stores providing nitrogen filling as a gimmick to attarct customers.

See

Ed

Wow - terrible advice!

Ed

Well, at least they sent cars out the door with pressure higher than the usual 26-29 lb nonsense, a range which I have NEVER found to be effective. But beyond that, it's silly to assume 32 lbs is right for every car. With Toyos on my Taurus, 34 was the sweet spot. With Nokians on my Tacoma, it's

37-ish.