Words for the wise: over inflated tires

[XCELERATIONRULES]

A couple pounds of air is not going to affect handling too much.
I always run my tires slightly over inflated and never notice any handling problems,but then again I always drive like my butt is on fire.

 

[Summerwind]

It took me a while to notice this (DUH) but this spring after having my snow tires taken off, and all 4 normal tires rotated, it finaly "dawned" on me that my GMQ just wasn't quite riding like a large, heavy car. My brain finaly kicks in, and I check the tire pressure. The tire shop had inflated them to 35psi, my door sticker says 32psi...I bled a few lbs of air off, and "WA-LA" My big car ride is back, and handling hasn't suffered

 

[ZeeOSix]

Tire inflation specs from the manufactures are specified for a reason ... best to follow them. I always do and I get perfect wear and high mileage out of my tires on every vehicle I've ever owned. Of course, rotating tires every 7500 ~ 10K miles and checking/adjusting tire pressure often also helps.

 

[Spyder7]

Tire inflation specs also take into account worst case scenario: tread at the replace mark, load bearing = to what the tires are rated for, and speed = to what the tires are rated for.

None of which (in any combination) are likely in the real world. Therefore if over-inflating by a few psi improves mileage, without negatively affecting handling, then I think its a gain.

Where it costs over $50 here to fill my small 13 gallon tank (assuming a fill from empty, which I never do where the fuel pump is in the tank and gas is also used to cool it), I'm all for saving a few bucks on it by any reasonable means available. To that end, I also do some (safe) highway drafting, reduce idle time as much as reasonable (good to do in its own right anyway), and use some "pulse and glide," mainly in anticipating lights and coasting up to them (which also reduces wear on the brake pads).

Individually, none of it saves a whole lot of gas; but collectively, it adds up and it also reduces wear and therefore total cost of ownership.

-Spyder

 

[rslifkin]

Spyder - That's the way to do it! Following a few of those tips on ecomodder can add up to a pretty noticeable difference. I can get 12 - 13 mpg around town from the Jeep that way (rated for 11), and 13 - 15 around town in Mom's 6 cylinder Grand Cherokee.

 

[Spyder7]

Originally Posted By: rslifkin
Spyder - That's the way to do it! Following a few of those tips on ecomodder can add up to a pretty noticeable difference. I can get 12 - 13 mpg around town from the Jeep that way (rated for 11), and 13 - 15 around town in Mom's 6 cylinder Grand Cherokee.


I don't recall which hyper-mileing site opened my eyes to this stuff (or even how I came across it), but when I first got this car, my fills were consistently a few mpg below the 30 mpg it was rated for when it left the factory.

Anyway that led to stumbling upon one of those sites, and my eyes were opened to all my bad driving habits I'd picked up over the years: aggressive stop and go driving that was little more than accelerating hard from one light just to have to brake hard for the next; neglecting to monitor tire pressure unless it was noticeably low; passing just for the sake of passing; etc.

I think the very first tip I followed was over-inflating my 35 psi tires to 42 psi (which also improved handling, and particularly cornering). Then I began to work on my driving habits, and the gains at the pump began to follow. Now its become integrated to the point that I do it unconsciously. And I figure over the lifespan of the car, the savings at the pump and in avoidable repairs due to excessive wear and tear, will be fairly significant.

-Spyder

 

[shpankey]

Originally Posted By: Pesca
Put pure Nitrogen in them instead of regular air.
That is what I did in my summer and winter sets, and they don't deflate anymore when stocked waiting to be used.
Summer tires are set at 42 psi.

My car came with Nitrogen from the factory but once I got a flat I had to repair it. Didn't know where to get the Nitrogen from so I had to use air. With the Nitrogen all my tires always stayed perfect, but with air the pressure goes up and down with the temp of the tires.

Anyhow, where do we get the Nitrogen to put in our tires? I'd love to go back to that!

 

[Spyder7]

You guys have really seen a difference with it eh. I'd always been a nitrogen skeptic, now I'm beginning to rethink that. As to the where to get it: any big chain that sells and installs tires will likely have it. Maybe I'll shop around a bit this week and see where I can get a decent price on a nitrogen fill (going back to 42 psi is very appealing when I can just fill and forget).

-Spyder

 

[SteveSRT8]

Nitrogen is pure snake oil at its finest.

 

[Spyder7]

That's what I always thought too, but these guys have seen otherwise. I try and keep an open mind (not always easy to do). If it is, I won't waste my money on it. But if it has some merit to it, I'll try it.

-Spyder

 

[Pesca]

Originally Posted By: shpankey
Anyhow, where do we get the Nitrogen to put in our tires? I'd love to go back to that!


Phone some mechanic shops around to ask if they do it, that is how I found mine (they were stupid people but at least I got my Nitrogen).

One important point: Nitrogen needs to come from a compressed bottle (100% Nitrogen), not from a compressor/separator.
Reason is, when you removed the air from the tire before putting Nitrogen, you cannot remove all the air. So, when you fill it up with 100% Nitrogen, you will get at the end about 95-97% Nitrogen in your tire.
Starting with a compressor, your starting % is about 92-95% and not 100%, so you end up with about less than 90% of Nitrogen. Since air is about 78%, the gain is not that obvious, which lead some people to think it doesn't work.

As for SteveSRT8, you got your opinion, and I have mine, but mine is based on facts (two winters and two summers of facts, actually).
My tires are inflated at 42 psi for summer and 33 (recommended) for winter, and in two years time, the only thing I do is take note that nothing has changed since last time I checked. Before, my stocked tires were deflated when I was switching them which was an hassle (remember to inflate them before changing tires).
For my wife's car, I did not put Nitrogen in them as I don't have dedicated rims, and every two-three months, I have to inflate them as they are too low.

 

[rslifkin]

Whether or not nitrogen is beneficial may depend on the tires. Some hold air better than others, so in some, nitrogen may be beneficial in tires that tend to seep air out faster.

 

[XS650]

Originally Posted By: rslifkin
Whether or not nitrogen is beneficial may depend on the tires. Some hold air better than others, so in some, nitrogen may be beneficial in tires that tend to seep air out faster.


Either Oxygen leaks out of tires faster than nitrogen...in which case your tires will soon have nearly pure nitrogen in them, in which case there is no reason to fill your tires with nitrogen.

Or, Oxygen doesn't leak out of tires significantly faster the nitrogen, in which case there is no reason to fill your tires with nitrogen.

If you really believe the differences in leakage rates claimed, just overfill you tires by 20% and by the time they leak down to rated pressure, they will have as good an N2 concentration as tire filled from an N2 bottle.

Tires filled from an N2 bottle are still about 7% Oxygen unless you go through multiple N2 fill/bleed cycles

 

[Kestas]

This thread has morphed into a nitrogen debate. If you have something to say about this, please add to the existing nitrogen debate:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=807851#Post807851

 

[ekpolk]

Originally Posted By: SteveSRT8
Nitrogen is pure snake oil at its finest.


A tad overstated, don't you think? Maybe for a pure street car that is never pushed to the boundaries, nitrogen may be a waste, but the more you push, toward the edges of the envelope, the more benefit it will provide. I don't bother with the stuff myself, but for a relatively small slice of the driving population, it has value. The stability of the gas, its dryness, etc., are all factors that may be of value for performance-oriented applications. Obviously, aircraft and cars are different animals, but it bears mention that virtually ALL high performance jets (and many light aircraft as well) require the use of pure Nitrogen in their tires. Nitrogen's performance, under extremes of speed, temperature, and pressure operate to remove some of the stress from the tire itself.