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DannyZ
Gentoo Fanboy
Premium Member
join:2003-01-29
united state

DannyZ to MooJohn

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to MooJohn

Re: Tire Inflation ?

said by MooJohn:

The "use the factory sticker" approach makes the huge assumption that the tire itself doesn't matter. As long as you have a round tire with x psi, you're fine. That's not something I'm willing to blindly concede.

There is no way that the ideal inflation for one tire is the ideal for all on a given vehicle. If you change from a 16 to a 17 inch wheel, is that cushy 29 psi still ideal? If you go from a $50 no-name tire to an expensive Pilot Sport, is 29 still ideal?

My last car had different guidelines for different rim sizes on the placard. Also, If you stick to the ratings of the stock tires, PSI should remain the same. Obviously, if you get a tire with a different load index and/or speed rating, the handling characteristics will be different and might require a PSI adjustment to obtain similar wheel response.

TheTechGuru
join:2004-03-25
TEXAS

TheTechGuru

Member

One should note, THE PSI NUMBERS ON THE DOOR STICKER ARE INTENDED FOR THE TIRE SIZE PRINTED ON THE DOOR STICKER! DUH!

Sorry I didn't say that when I said to use the door sticker, I over estimated everyone's intelligence and just assumed everyone was intelligent enough to figure that out.

DannyZ
Gentoo Fanboy
Premium Member
join:2003-01-29
united state

DannyZ

Premium Member

said by TheTechGuru:

One should note, THE PSI NUMBERS ON THE DOOR STICKER ARE INTENDED FOR THE TIRE SIZE PRINTED ON THE DOOR STICKER! DUH!

It's also optimized for the tire rating, which isn't usually represented on the placard as far as I've seen. That was mostly my point, I was agreeing that different quality tires may have different sweet spots.

MooJohn
join:2005-12-18
Milledgeville, GA

MooJohn to TheTechGuru

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to TheTechGuru
said by TheTechGuru:

One should note, THE PSI NUMBERS ON THE DOOR STICKER ARE INTENDED FOR THE TIRE SIZE PRINTED ON THE DOOR STICKER! DUH!

Sorry I didn't say that when I said to use the door sticker, I over estimated everyone's intelligence and just assumed everyone was intelligent enough to figure that out.

Ah ha! So at that point one's personal judgement is perfectly capable of determining the proper inflation pressure whereas with stock tires the same reasoning cannot be trusted. I am able to determine the proper pressure of aftermarket tires but if the car came with the same size from the OEM then I would have zero input.

Makes perfect sense.

Who knew such infallible automotive wisdom was contained on the little silver sticker inside the door jamb?

TheTechGuru
join:2004-03-25
TEXAS

TheTechGuru to Bob4

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to Bob4
said by Bob4:

My low pressure light came on last night. Drove home and I see all four tires are low (~27 psi, should be 32). So now I have to put air in, and I hate those new machines at the gas stations.

Everyone should own a basic tanked air compressor IMO.

»www.homedepot.com/Tools- ··· tDisplay
mob (banned)
On the next level..
join:2000-10-07
San Jose, CA

mob (banned) to MooJohn

Member

to MooJohn
said by MooJohn:

The "use the factory sticker" approach makes the huge assumption that the tire itself doesn't matter. As long as you have a round tire with x psi, you're fine. That's not something I'm willing to blindly concede.

There is no way that the ideal inflation for one tire is the ideal for all on a given vehicle. If you change from a 16 to a 17 inch wheel, is that cushy 29 psi still ideal? If you go from a $50 no-name tire to an expensive Pilot Sport, is 29 still ideal?

That doesn't even address the factors that make up the "ideal" point either. What is ideal? Is it the softest ride? Is it the minimum without risking tire damage? Is it harmonically tuned to the suspension resonances? We just don't know. At the recommended pressure, my car rides like a Lincoln -- because it is one. At 35 it rides the way I want it to. Guess where it's staying?

The sticker is ok for the OEM-equipped tires only. After that, using it might not get you killed but there's no way it is certain to be the ideal pressure either. There are just too many variables to accept it as gospel.

I switched from 18" rims to 20" rims. When I first had the 20" rims on, I ran the tires at 40 PSI, then went back to 35 PSI like the door jamb said after finding the ride to be too rough and having less grip than the smaller stock sized tires. Once I dropped the pressure on the tires the ride became close to what it was like on the stock rims and the grip went up dramatically.
Bob4
Account deleted
join:2012-07-22
New Jersey

Bob4

Member

said by Bob4:

I think I'll stop at Lowes and get one of these »www.lowes.com/pd_146781- ··· =3522750
(was mentioned in the other thread)

So I got the Kobalt unit. It's pretty nice, although noisy as hell. It has a digital PSI display. You just set the desired pressure, hit start, and it runs & shuts off automatically when the target pressure is reached.

Only thing that concerns me is that I can see sparks inside the unit when it's running. I guess it's the motor commutator??

shdesigns
Powered By Infinite Improbabilty Drive
Premium Member
join:2000-12-01
Stone Mountain, GA
(Software) pfSense
ARRIS SB6121

shdesigns

Premium Member

Yes, most compressors these days are real loud. The sparks probably are the brushes.

Hope it lasts; I never have had luck with those small compressors. I would have gotten a real one with a tank, but they start near $100.

I have a small Kobalt 3 gal compressor I picked up off CL. It works ok but has a bit of burning smell when it works hard. Probably dust on the compressor. Don't use it much as I have a big compressor for the garage.

Rifleman
Premium Member
join:2004-02-09
p1a

Rifleman

Premium Member

These tires are W rated for speed. I'm 6 pounds over the sticker recommendation on the car and 12 under the tire's recommendation. It seems good to me by the seat of the pants feeling. I do get that weird harminic noise at 45--50MPH but wondering if it may be a wheel bearing. My hearing is badly impaired so hard to tell. I'll get it checked out when I change the oil next week.

Lurch77
Premium Member
join:2001-11-22
Green Bay, WI

Lurch77 to TheTechGuru

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to TheTechGuru
said by TheTechGuru:

One should note, THE PSI NUMBERS ON THE DOOR STICKER ARE INTENDED FOR THE TIRE SIZE PRINTED ON THE DOOR STICKER! DUH!


You are confusing air volume with air pressure. There are other factors to consider when determinging pressure, but the basic size of the tire has little to do with it.
»blog.tirerack.com/blog/t ··· ire-size
Bob4
Account deleted
join:2012-07-22
New Jersey

Bob4 to Rifleman

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to Rifleman
said by Rifleman:

I'm 6 pounds over the sticker recommendation on the car and 12 under the tire's recommendation.

I think you mean to say "tire's maximum".

Rifleman
Premium Member
join:2004-02-09
p1a

Rifleman

Premium Member

Yeah. I guess. It's working Ok for me so will leave it as is. drove a hard 2600kms in 4 days on them with no problems.

Beezel
join:2008-12-15
Las Vegas, NV

Beezel to Bob4

Member

to Bob4
said by Bob4:

said by Bob4:

I think I'll stop at Lowes and get one of these »www.lowes.com/pd_146781- ··· =3522750
(was mentioned in the other thread)

So I got the Kobalt unit. It's pretty nice, although noisy as hell. It has a digital PSI display. You just set the desired pressure, hit start, and it runs & shuts off automatically when the target pressure is reached.

Only thing that concerns me is that I can see sparks inside the unit when it's running. I guess it's the motor commutator??

Most oil-less compressors are very noisy. Sparks are normal with most electric motors.