Airing down/up and tire temperatures

[rickl]

Just got a Viair pump so I can air down/up easily. I've read a lot on the web, including on this forum, about equipment and preferred air pressures. Went to a local moderately nasty road to test everything out before I really need it. Running KO2s (stock size), cold pressure at home 33 psi, intended to air down to 24 for this road test. Got to the road and realized something I hadn't read about in any posts. Of course, the pressure had increased during the drive over to about 36.

So the question is: How to others approach desired air pressure when the tires aren't cold. Should I have aired down to, say, 27 to compensate? When airing back up, I've been on a dirt road at low speeds, so tires will be cooler, but not cold, so what should I air back to? Or am I overthinking this and precision is not that critical.

Thanks in advance for your thoughts.

 

[JAXJeremy]

personally I think you're overthinking it..tire pressures will fluctuate a couple of Psi either way depending on temps, it's not really that big of a deal..just as long as you don't have any leaks..

 

[BobsTrail]

I agree with [MENTION=268621]JAXJeremy[/MENTION]. I run 15 for soft sand and 20 for trails. I air up to 32 and check it again the next morning. Works well for me.

 

[rickl]

JAXJeremy and BobsTrail, thanks, good to hear and I appreciated the voices of experience. Certainly simpler not to stress over a few pounds.

 

[03_4x4Runner]

Set the pressure to the normal pressure cold. After driving around on the street till they are hot check the tire pressure. It will be higher. When you air up after being aired down set the pressure to the normal hot pressure and you will be close.

 

[grizzlypath]

personally I think you're overthinking it..tire pressures will fluctuate a couple of Psi either way depending on temps, it's not really that big of a deal..just as long as you don't have any leaks..

No way man, I always adjust to compensate for changing pressures due to temperature and conditions. I use this quick handy dandy chart.

 

[Whippersnapper02]

I drop to 20psi when needed then back up to normal pressure when I'm done and recheck when the tires are cold. Generally they need a couple of pounds when cold.

 

[honda250xtitan]

JAXJeremy and BobsTrail, thanks, good to hear and I appreciated the voices of experience. Certainly simpler not to stress over a few pounds.

we ran ours at 20PSI all week in baja. included all types of driving INCLUDING highway stretches. running E or C rated tires gives you flexibility since the toyotas are so light

 

[rickl]

No way man, I always adjust to compensate for changing pressures due to temperature and conditions. I use this quick handy dandy chart.

grizzlypath, can you post or link the chart?

It does seem like airing up is the potentially more critical part, and I wonder how critical it is within a few pounds for one day (until you can check cold). I know every time I take it in for service, they seem to inflate to a different level (need to talk to the dealer about that!), from 32 to 37 (didn't even realize it until I recently looked at the service records). That's been the case since I bought it 7 years ago and I haven't experienced noticeable uneven wear.

 

[Cndnmax]

Btw: hot tires = higher pressure. those portable compressors heat up fast and pump in hot air anyways. you don’t want to go low, Just bring them up to your regular pressure and check it again when cold. A couple psi is negligible.

 

[4Reak Show]

Well this is easy (sigh) but let’s make sure:

104° X 24 psi (^3.1415972) / [285/75R16 {@ Load rating “E”]} - circumference X R^3 (to compensate for elevations shifts and autumnal reverberations) = stop worrying and have fun.











Yup math checks out on my end.

 

[Hyde802]

^best answer yet. Haha.

 

[Captain Planet]

After driving on the beach for a while at 15PSI, I'll air back up to 37.

Once they cool back down, they are usually at 34 cold.

Keep in mind, they are going to get hotter faster at lower pressures.

 

[rickl]

Well this is easy (sigh) but let’s make sure:

104° X 24 psi (^3.1415972) / [285/75R16 {@ Load rating “E”]} - circumference X R^3 (to compensate for elevations shifts and autumnal reverberations) = stop worrying and have fun.



Yup math checks out on my end.

Can't argue with math, I'm convinced.

 

[Brick Sprickly]

We had this issue a few months back on a multi-day trip with another forum member to SE OR. Being in the desert we'd encounter significant temp fluctuations which would also shift psi ~12-15 throughout the day. Combine this with mountainous elevation changes and you'll see lots of differences. Just check it here and there if you're concerned, but as said above, if there's no leak it's not really a problem.

 

[ElectroBoy]

We had this issue a few months back on a multi-day trip with another forum member to SE OR. Being in the desert we'd encounter significant temp fluctuations which would also shift psi ~12-15 throughout the day. Combine this with mountainous elevation changes and you'll see lots of differences. Just check it here and there if you're concerned, but as said above, if there's no leak it's not really a problem.

Yup. Don’t stress about it too much.
On a recent southern Utah off-roading trip I aired down to 24 PSI at the trailhead in the morning, air temp was 70F. At the end of the day the air temp was 98F. I was prepared to air up for the pavement but all tires were at 32 PSI so I just drove it back to my lodging. Checked cold tires the next day and brought them up to 34 PSI.

 

[<<<<]

For seasonal temperature change: roughly 10' F temp drop equals 1 PSI drop in your tires.

 

[4r-4ever]

just set it to 35 when you inflate after a good ride. the normal pressure is 32. 20 when off roading. 15 when in the sand. 32 when inflating it when the car is not driven for a few hours.

 

[DAW89446]

I run an ‘18 SR5 with stock size BFG All Terrain T/A KO2’s, load range E. To date, I’ve not dropped from street pressure, 45 psi. That’s because I’m getting older and don’t do as much off roading as I used to.

That said, for years I ran a 2002 Tacoma TRD with stock size BFG’s, load range C. I ran 35 on road, 18-20 off road. Pressure read both when airing down, airing up. I never bothered to allow for tire temperatures. Heck, many times I’d simply run the highway with my tires at off road pressures so I didn’t have to wait 45 minutes waiting for my 12V plug in pump to get back to street pressure, instead airing up with my shop air compressor at home. Those tires took a beating with no ill effects and gave me generally 70,000 miles.

Now, I don’t suggest that others run with low pressures on the highway. What I’m saying is that a few pounds for the short term doesn’t matter; reflecting what others have said here. For accuracy, before you take your rig out the next morning, simply do a quick check and adjust if necessary.

 

[4r-4ever]

you need to upgrade to bigger 12v air pump, . driving at highway speed with low pressure is dangerous or maybe too much pressure is more dangerous. you have the best traction though on pavement with lower pressure and lower mpg. lol!

I run an ‘18 SR5 with stock size BFG All Terrain T/A KO2’s, load range E. To date, I’ve not dropped from street pressure, 45 psi. That’s because I’m getting older and don’t do as much off roading as I used to.

That said, for years I ran a 2002 Tacoma TRD with stock size BFG’s, load range C. I ran 35 on road, 18-20 off road. Pressure read both when airing down, airing up. I never bothered to allow for tire temperatures. Heck, many times I’d simply run the highway with my tires at off road pressures so I didn’t have to wait 45 minutes waiting for my 12V plug in pump to get back to street pressure, instead airing up with my shop air compressor at home. Those tires took a beating with no ill effects and gave me generally 70,000 miles.

Now, I don’t suggest that others run with low pressures on the highway. What I’m saying is that a few pounds for the short term doesn’t matter; reflecting what others have said here. For accuracy, before you take your rig out the next morning, simply do a quick check and adjust if necessary.