When inflating tires to the recommended tire pressure 29/30, are these numbers for cold tire pressure before the car is being driven, or after the car has been driven?
Speaking of tires?
Nov 11, 2006
8 Replies
First reply
Don't be afraid to increase that number by 5-10 percent(maintaining a fron/rear difference). Often, a tire will be low by the time you recheck them, any extra load (vacation - carpooling, etc.) will heat them up more so xtra pressure is needed, and, most cars just handle…
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Cold.
Don't be afraid to increase that number by 5-10 percent(maintaining a fron/rear difference). Often, a tire will be low by the time you recheck them, any extra load (vacation - carpooling, etc.) will heat them up more so xtra pressure is needed, and, most cars just handle better. I THINK some car manufacturers err on the low side because the car rides more softly.
do not exceed the number on the sidewall.
Carl
Thanks. I had been messing with the figures somewhat, inflating upto a
34/35 down to a 29/30, etc. My goal was to see if it affected my gas mileage or softened the ride any. I was curious how much leeway I was allowed and also because after my 90k servicing at the dealership, I noticed that the tires were deflated to 24/25 so that made me wonder if the 29/30 was a hot temp.
Cold, or at least within first 5Km/3Ml is good. I'm running 32F/35R on an OBW & it works well. Cheers
It may be a little more critical on AWD cars to help reduce the chance of torque bind. The car does not, after all, have 50/50 weight distribution.
I doubt it would be a big issue though. Some of the guys at the autoX I was in this weekend run the same on all 4 corners. But then they re-adjust for the drive home.
Carl
Depends on the kind of driving you are doing and the temperature. I run the same pressures all around on the highway, but if I am driving on the twisties, I put 6PSI more in front than in the rear. It helps reduce understeer.
Hi,
As everyone's already told you, these are "cold" pressures. I think you'll generally see "cold" defined as having sat for at least 3 hrs or driven less than a mile or so (these numbers will vary according to source.)
For myself, I consider the door sticker to be MINIMUM pressures. Many people find they get better mileage (both fuel and tire) and/or handling with higher pressures. Experiment for yourself, going a pound or two at a time, to see what works best for you and your driving style. As another poster mentioned, highway conditions aren't the same as mountains, etc. A trusted tire guy once told me to always go about 2 psi over the door sticker (as long as it doesn't exceed the tire sidewall rating) to account for the widely varied temps we have on a daily basis here in SoCal. YMMV on that issue.
And get a GOOD gauge! Some folks like digitals. I have one, but prefer the Accu-Gage to all others I've used. Some of the better shops sell them, or you can go online to
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. When adding air, I've seen it recommended for decades to always go a bit high, then bleed down to the desired pressure. The Accu-Gage and some others have a built-in bleeding capacity that makes them really easy to use for that purpose.
Rick
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