Dumb question, but what's the correct tire pressure?!

I don't subscribe in the chalk test. 12 inch wide 35 tall tires on 8 inch wheels on a jeep and your chalk test is going to show 16-18 psi. Google the 4 psi rule. Better indicator of where your pressure should be or go high tech and do it how autocrossers do it, with an infared thermometer reading on your tread, inside, center, outside...

 

My '18 came from the factory with 38psi all around. I'll have to do a chalk test on it to see if that is right

 

I don't subscribe to the chalk test. Seems to me the faster you go the more deformed or taller the tire gets due to centrifugal force. At low speeds where the chalk test is performed the tire doesn't deform. If you call the manufacturer or look on thier website, they will have a tool to input your truck data and give you the exact tire pressures for your situation.

 

where can I find solid guidance on reducing air pressure for off road? what's your experience?

found many websites discussing this, but none specific for Tundras. some talk about dropping really low (10 psi).

I have the stock Michelin P275/65R18 tires with recommended max of 44 psi.

 

Tinker with the pressures and figure it out on your own. Every vehicle and tire is different as well as conditions so solid guidance is different. Best to mess around. Start with your regular pressure and work down if you get stuck or want more cushion.

 

I run 40 in all mine but I swapped the street tries for BFG KO2.

 

The whole dropping pressure to single digits is generally left to very light vehicles or to those running beadlocks. On a heavy tundra, with no beadlocks, I’d have a hard time recommending going under 20. Reason being is that the heavier the vehicle, the more momentum present and say you dropped off a ledge, that momentum would over power the strength of the pressure inside the rim to keep the bead seated on the wheel. However, that weight also works to your advantage. I say this because since the truck is so heavy, it doesn’t take much pressure to be let out, for the weight to overcome the force of the tires sidewalk and force it to bulge.

Moral of the story is, don’t lower so much that you risk popping a bead. Popping a bead on the trail sucks!!

This is good advice. Generally you want to play with pressures, depending on your load out and weight. You want a slight bulge to increase Offroad traction and comfort, but not so low that the tire is folding over itself or you pop a bead. Always play it on the safe side though. It’s safer to have a little higher pressure and struggle with traction on an obstacle, than having all the traction and blowing out a bead. It’s also best to do this on dirt or snow. At some point, lowering the pressure has deminishing returns and it’s visible in your tread pattern.

 

It's difficult for you because you're just medium lazy. If you were full blown lazy like me, your garage floor would be very dusty which acts as a natural chalk test just driving into the garage. That's how I did my chalk test.

 

My truck is heavier than stock so I do 36 all around.

 

40 all the way around. They are wearing great.

 

Here's the deal. For those who don't have the time or inclination to do the chalk test. This is not rocket science. Don't follow the door panel pressures. Tires get changed. The tire manufacturer puts the psi for optimal highway driving right on the tire. There's your test. Best even wear, mileage, and life saving response. For those who run under that for comfort or dirt roads, you are putting your life at risk when on the highway.

 

35 Psi front and back (max psi is 44) Michelin LTX

 

Update. I used to run sidewall stated max, with no problem I might add. No uneven wear, no blowout. That's only happening with a cheap tire.
Tundra recommends 30psi for my truck. I'm trying it for a tank to get the mpg. So far It looks like it's on track to get the same. That being said, my tires now squish out at the bottom. Yes, it may be comfortable, but I am smart enough to know I will Never get the life out of these tires running on the sidewall. After this tank I will up the pressure until they look like a perfectly formed tire, (no bulge).
I look for my money's worth and mpg from my tire, and that is how I will get it.
Anyone who rides on their sidewall for comfort is throwing away money.

 

Update. At 30psi my mpg went down to 17.6 from 19 at 50psi. That would cost me approximately $300 more per year to run squishy tires. It's not worth it to me combining the increased wear on the tire from running on the sidewall. Tires are expensive. Back to 50psi I went.

 

I run the same tires as yours in the picture (Defender LT's) Theyre max PSI Is 80 they read the pressure on the tire not your door NEVER LOOK AT THE DOOR FOR PSI Always look at the tire because it is rare that a used car will have stock tires on it, your tires should be at the 45-55 range when not towing and they are rated for towing not everyday use

 

35 psi

 

Sorry to pile on late, but I've found this converter to be really helpful. After I installed my lift and 295/70R18 tires, this helped me determine my tire pressure.

 

275/70/18 BFGs… running them at 40psi.

previously always ran stick 33 pressure… going to see how this impacts mpg and ride.

 

That size Michelin Defender LTX m+s 2, is NOT an actual LT (Light Truck) tire. I think it has an SL (Standard Load) rating, and if you check the small print on your sidewall it will give you a maximum inflation pressure, and a maximum load in pounds for the tire. So you can support the max load with the max pressure listed. I think it might be 44psi maximum. Can you post a photo of your door sill label?