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.

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..

I agree with @JAXJeremy . 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.

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

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.

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

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.

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

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.

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.

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.

^best answer yet. Haha.

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.

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

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.