That's why you use Nitrogen, more constant pressure. Most specialist tyre shops have it here.
How picky are you?
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On another thread I read that you should consider the A-pillar placard as a rough MINIMUM pressure.
I know I like my tires way overinflated for what Toyota calls ideal.
Yes I feel every little bump but I'm not that picky.
I also agree that raising the tire pressure is like raising the spring rate (the tire is actually more like a spring than a shock absorber) at that corner. Most passenger cars are undersprung and underinflated at standard settings (for performance--like someone else said they are calibrated more for comfort than for performance).
I know I like my tires way overinflated for what Toyota calls ideal.
Yes I feel every little bump but I'm not that picky.
I also agree that raising the tire pressure is like raising the spring rate (the tire is actually more like a spring than a shock absorber) at that corner. Most passenger cars are undersprung and underinflated at standard settings (for performance--like someone else said they are calibrated more for comfort than for performance).
My practice on most vehicles is to start at 34 PSI on each wheel and work upwards from there as it moves me. On the Winter Mazda that means about 34 -36 and on the Porsche about 38 PSI. I don't worry about deviations of .5 PSI or so as I expect the accuracy of the guages is not there.
Like AEHaas I have a bazillion cheap gauges. I tossed the one that read about 4 PSI lower than all the others, so at least I can measure consistently. In each car including my girlfriend's I have placed at least 1 gauge and a 12v compressor inflator that have terribly vague dial gauges that at least are roughly consistent to within around 1 PSI.
I check pressure on my cars about every week to 10 days and on my girlfriend's car pretty much any time I drive it. Not because I am being conscientious, but because every time I drive it, I pull over after half a mile and check the tire pressure. I usually find at least 1 or 2 tires 10 PSI or so low.
Like AEHaas I have a bazillion cheap gauges. I tossed the one that read about 4 PSI lower than all the others, so at least I can measure consistently. In each car including my girlfriend's I have placed at least 1 gauge and a 12v compressor inflator that have terribly vague dial gauges that at least are roughly consistent to within around 1 PSI.
I check pressure on my cars about every week to 10 days and on my girlfriend's car pretty much any time I drive it. Not because I am being conscientious, but because every time I drive it, I pull over after half a mile and check the tire pressure. I usually find at least 1 or 2 tires 10 PSI or so low.
Better from a safety standpoint to be overinflated by 20% than to be underinflated by 10% vis-a-vis the VEHICLE manufacturer's recommendation, IMHO.
The tire can normally safely withstand much more additional air pressure than the vehicle can compensate for underinflation.
This goes especially for motorcycle tires.
CHEERS!
The tire can normally safely withstand much more additional air pressure than the vehicle can compensate for underinflation.
This goes especially for motorcycle tires.
CHEERS!
Norm Olt
Member # 951
posted December 26, 2005 11:10 PM
"Better from a safety standpoint to be overinflated by 20% than to be underinflated by 10% vis-a-vis the VEHICLE manufacturer's recommendation, IMHO. "
That's not necessarily true. If you have too much air pressure, you're not riding on the full tread of the tire anymore. The same goes for underinflation. Following the tire placard for the given size is the best way to go.
Member # 951
posted December 26, 2005 11:10 PM
"Better from a safety standpoint to be overinflated by 20% than to be underinflated by 10% vis-a-vis the VEHICLE manufacturer's recommendation, IMHO. "
That's not necessarily true. If you have too much air pressure, you're not riding on the full tread of the tire anymore. The same goes for underinflation. Following the tire placard for the given size is the best way to go.
"If you have too much air pressure, you're not riding on the full tread of the tire anymore."
This is surprisingly hard to do. Impossible if you are within the markings on the sidewall. The pressure on the sticker is usually lower than the max pressure of the tire.
This is surprisingly hard to do. Impossible if you are within the markings on the sidewall. The pressure on the sticker is usually lower than the max pressure of the tire.
It's not too hard to do. Example: My Jeep YJ runs 35/12.5R15 Mickey Thompson Baja Claws. If I filled 'em up with 32 PSI, it would ride pretty rough (i.e. stiff), but the tread would still make full contact. If I added, say...20% more air and went to 38 or 40 PSI, the tire will slightly crown and only the center will have contact. Dropping 10% (from the 32PSI "norm"), leaves me at 28-29 PSI, which is better.
I actually run 20PSI on the street, which is optimal for ride quality and showed the best street contact with my chalkline test.
Anyway, I'm not saying ALL tires will start to crown, I'm just saying it's possible in some applications and having too much air could be just as bad as not enough.
I actually run 20PSI on the street, which is optimal for ride quality and showed the best street contact with my chalkline test.
Anyway, I'm not saying ALL tires will start to crown, I'm just saying it's possible in some applications and having too much air could be just as bad as not enough.
Patman
Staff member
245-45-17 in front, 275-40-18 rear
Chefwong, bottled nitrogen is used because it contains no moisture - it is the h2o vapor in ordinary air that causes a steeper pressure rise with temperature increase, not the type of gas itself. Nitrogen is (fairly) cheap and inert, and a nitrogen tank can be used to run air tools if there's no compressor available (a popular pit/paddock approach).
That said, I've never used nitrogen in tires - I don't see the need for it on the street, and givent the type of track driving I usually do, I adjust for the proper hot pressure and just try to remember that it takes a couple of laps for the temp/pressure to come up.
That said, I've never used nitrogen in tires - I don't see the need for it on the street, and givent the type of track driving I usually do, I adjust for the proper hot pressure and just try to remember that it takes a couple of laps for the temp/pressure to come up.
'Talk about tire size, the Murcielago has 295-30-18 in the front and 345-30-18 in the rear I think. I run around 42 lbs. in each.
aehaas
aehaas
I'm so anal about it, I won't try to correct the tire pressure if one side of the car was in the sun.
Having the right side adjusted, I was in a hurry this morning adding psi in the left side tires of my Passat..coz the rising sun was about to hit that side.
Then again, I also admit to picking pebbles out of the tread...
Guilty as well(pebbles ruins the balance)..
[ December 28, 2005, 12:04 AM: Message edited by: vwoom ]
Having the right side adjusted, I was in a hurry this morning adding psi in the left side tires of my Passat..coz the rising sun was about to hit that side.
Then again, I also admit to picking pebbles out of the tread...
Guilty as well(pebbles ruins the balance)..
[ December 28, 2005, 12:04 AM: Message edited by: vwoom ]
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Patman, what's the tire size, front and rear, on your Vette?
My Jeep sees 6PSI on the trail and 18-20 PSI on the street. Perfect.
My Malibu Maxx LT sees 30 PSI/cold all around.
My Malibu Maxx LT sees 30 PSI/cold all around.
What is wierd is that new tires from tire shops tend to come out LOW. Maybe it's those "millitary-style" guages they use. 20-25lbs is what they let people drive out with, sorta dumb.
Maybe they have thier compressor set low to keep thier employees from making it impossible to get your lugs nuts off(air tools)...and low air preasure in your tires is the lesser of the 2 evils?
I never trust them tire shop gauges. These built in air gauge/nozzles of any type are always dropped(Gawd knows how many times..)on the floor(imagine the accuracy, if any.).
Which is why whenever I do go to the tire place, I always make it a point to adjust the psi myself correctly using my tire gauge before the car leaves the shop garage.
Talk about being anal..
Which is why whenever I do go to the tire place, I always make it a point to adjust the psi myself correctly using my tire gauge before the car leaves the shop garage.
Talk about being anal..
I have also found that the sun side is typically 2-3 pounds higher. Dry air is just as good as nitrogen. Air is 18% nitrogen so no difference.
Perhaps that was a typo, Eddie? Nitrogen comprises 78% of the earth's atmosphere.
That is pretty dumb. Maybe they are overcautious on the down side for some reason.
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