Tire pressure question

I know tire pressures go up as they heat up..and tire pressure should be checked when cold. So with my new CCW's and Pilot Sports, I have them at 32 cold with a guage not the sensors but the sensors agree 32.
After a few minutes of driving they all show 35-36. That seems like a lot. I am used to the runcraps that barely crossed 34. We haven't even gotten in to high temperatures and scorcing roadway temps yet. Anyone think I need to be worried or anyone with similar experience?

I keep my tire pressure at 30 psi. After a short drive they are at 33 psi w/the outside temps at 75-80.
Don

35-36 when warm sounds about right for best tire wear. If you want a smoother ride drop them down to 29 or 30 psi when cold. Normally it takes a tire 1 mile to increase 1 psi and they usually don't go any higher than 4 psi under normal driving conditions. If you do a lot of high speed driving w/ tires that aren't rated for high speeds, they'll get higher than 4 psi and sometimes will pop. Most of us Vetters put on tires that are rated for 149+mph so a 4 psi increase is about the most we will see no matter what the outside or road temps are.

You ever watch the police chase vids on tv? Most of the cars that have blowouts are from doing 100+ mph on tires that aren't designed to go that fast for an extended period of time.

on my lil' hatchback I keep my pressures around 40 up front and 36-38 in the back...haven't had any problems with such pressures...

my runflats start out about 28 /29 then heat up to about 30 all 4 are exact same most of the time. im not sure how accurate those sensors are. but gotta be more accurate then the old fashon type pencil gauges.:huh:

I noticed something funny about guages. I checked my tire pressure at the same time using 3 different guages.

#1http://www.northerntool.com/images/product/images/159355_lg.jpg

#2http://www.getagauge.com/graphics/HseriesGauge.gif

#3http://static.howstuffworks.com/gif/pg-intro.jpg

Guage #1 showed the highest pressure and guage #3 showed the lowest pressure so I always check mine w/ guage #2. There was a 4 pound difference between #1 and #3.

i read that it is ALLWAYS better to have more air than the recmended than less air than the recmended amount


oh and if you only get two new tires put the less worn ones on the back (front or rear wheel drive, it does not matter)

Once after an oil change I got in the car and they had filled my tires to 45psi. It was like driving on beach balls until the computer started beeping constantly. That's a pretty big mistake to make...

Mine are around 31 - 32 at highway speeds during the warmer months.

Originally posted by inspiron
i read that it is ALLWAYS better to have more air than the recmended than less air than the recmended amount


oh and if you only get two new tires put the less worn ones on the back (front or rear wheel drive, it does not matter)

for some cars, thats not possible.

Originally posted by lehmannhenry
on my lil' hatchback I keep my pressures around 40 up front and 36-38 in the back...haven't had any problems with such pressures...

That is over doing it by quite a margin! You may not have had any trouble yet but you have upped the odds that you will. Not to mention the increased tire wear in the center of the tire and overly harsh ride that jolts your whole car, even if you don't mind I'll bet your car does!

Consider too that after a few miles you may see pressures in the 45lbs range, which is about 10 to 12 lbs over the reccommended tire pressure.

here is a thought instead of air use nitrogen, i think its more stable . and some places would charge a small fee to pump up your tires. :partyon:

Originally posted by Bart
here is a thought instead of air use nitrogen, i think its more stable . and some places would charge a small fee to pump up your tires. :partyon:

yes but it is only worth the money if you get the tires filled when they are new and have not been filled with air yet



i got that little tidbit from a popular micanics mag

I am a nut about tire pressure. I check mine in every car all the time. The Corvette more because with the driving club we are in, we do very aggressive driving. I always follow the manual or info. somewhere on the car for cold PSI and adjust accordingly using the manual guage. The Corvette throws me because of the sensors and it seems they are not truely accurate until after driving so many miles. So use the tire guage. Have researched enough to know 4 PSI is a normal raise when hot. Yesterday, after a very long aggressive drive, that is exactly what the readout from the sensors read over from original cold PSI on a 83 degree day. I have also been through that tire pressure guage difference thing. Now that will really drive you crazy.

Laurie

Driving my '04 convertible back home from the Museum Delivery, my tires were 32 psi cold and only went to a high of 36psi after hours of interstate driving. I'll keep them at 32 cold and check the wear periodically.:thumbsup:

Originally posted by RF Hayes
That is over doing it by quite a margin! You may not have had any trouble yet but you have upped the odds that you will. Not to mention the increased tire wear in the center of the tire and overly harsh ride that jolts your whole car, even if you don't mind I'll bet your car does!

Consider too that after a few miles you may see pressures in the 45lbs range, which is about 10 to 12 lbs over the reccommended tire pressure.

hmmm...probably true...i used to keep them around 30-32 cold, but the car understeers really hard around town unless i keep them around 40. When I go for a highway drive i drop them to about 35 cold. When I get different rims and lower profile tires I'll be keeping them in the mid to lower 30s (I'm running P195/60R14s now...hoping to get something like 16 or 17 inch rims with a nice set of tires)

Originally posted by lehmannhenry
on my lil' hatchback I keep my pressures around 40 up front and 36-38 in the back...haven't had any problems with such pressures...

Are they supposed to be that high? I think that'd be a bone jarring ride. Are your teeth still intact?

here's an interesting experiment for you to try .....

step 1
check your air pressure first thing in ther morning

step 2
step park the car in the open on a sunny day

step 3
without ever having driven the car that day check the air pressure at noon

you will find the tires on the side of the car that were subjected to direct sunlight will have pressures 2 or pounds higher than the other side

well since I already gave you the conclusion I guess it's not really an experiment

now on to the real issue of this post:

tires heat up because they flex when you are driving and runflat tires do not flex as much as non-runflat tires because of the dtiff sidewall design .... what you have noticed is not uncommon and perfectly normal ... I have seen a 12 psi increase in under a half hour of driving before

Originally posted by Luke@tirerack
I have seen a 12 psi increase in under a half hour of driving before

:huh: What were you driving on, the Death Valley RR tracks? :surprised

A couple of weeks ago I drove steady for 8 hours on the interstate at speeds of at least 70 mph. It was non stop except once for gas and the outside temp was about 75 to 80 degrees (varyied the further north I traveled)

All day the tire pressure never gained more than 2-3 lbs and when it started raining (heavy rain) they dropped back to 30lbs. (GY run flats)

I supposed the conditions have a lot to do with it, and perhaps the tires were under infalted to begin with, but I would think that a 12 lb increase in 30 minutes would indicate an excessive amount of sidewall flex and a short lived tire. (Heat failure, delamination)

:cheers:

Gingerman Raceway = 1.9 miles 11 turns and triple digit speeds followed abruptly by some severe cornering and non-runflat race tires

Originally posted by Luke@tirerack
Gingerman Raceway = 1.9 miles 11 turns and triple digit speeds followed abruptly by some severe cornering and non-runflat race tires

That'll do it! But you have to admit thats not normal usage. :cheers: