Tire Pressure?

I have a 2019 SR5 with stock tires.

The door jamb says 29 psi, but they were bulging at the bottom sidewalls bad.

Last week I aired up to 32 psi, and there was still a noticeable bulge.

Yesterday I aired up to 37/38 psi, and the bulge is gone and the tires look properly inflated. It also drives and feels smoother and lighter now.

Why would there be such a discrepancy between Toyota's recommendation and what I see?

(FWIW, it's been in the 30s/40s F here)

 

38 seems high to me

 

My door jam says 29 too, back from my days working on the farm we never filled anything less than 35 for the trucks... to me 29 seems too low so I keep mine at around 31-32 for peace of mind.

Interestingly I found out that all tacoma trims come with different psi recommendations in the door jam.

 

Regardless of the perceived bulge which is ment to be there, I stay in the 32lb range and no more.....unless you carry a load.

The bulge is what makes the tread run flat. Otherwise, the center of the tire will wear faster above 35 psi with no load. Yes the tires roll easier with higher pressure. But, they have less traction and wear unevenly and faster.

 

I arrived at 38 front and 36 rear doing a chalk test. It also seems to understeer much less at those levels.

Any time I bring it to the dealer, they change it to 35 all the way around, despite the door jamb saying 29 psi.

 

The ride must really suck

 

35F/36R is what I run.

 

The 'bulge' at the bottom of the tire is normal and can not be accurately used to indicate low air pressure. This is a common trait for radial tires based on the way they are constructed. It allows the side wall to give more freely when encountering obstacles while driving. The amount of bulge can also vary depending on how the vehicle it sitting or what the tire is sitting on. The only true way to indicate tire pressure is a tire pressure gauge.

 

39F and 36R is what i run on my DCLB. Drives fine and rides fine on my toyo at2's. I have dropped pressure to around 32 before just to see what it was like and it wallowed like a SOB. The higher pressures work great for me.

 

30 psi front 25 psi rear, toyo rt's. No squish or wallow.

Edit: tread wear even so far.

 

Should also check the max PSI on the tire sidewall. Will be 35 or 44. Shouldn't go over that no matter what the internet says.

 

29 is the correct pressure for your stock tires.

 

Running a few PSI over door sticker recommended pressure is not a big deal as far as wear goes and does help the tires roll a tad easier helping a little with MPG. Especially so in cold weather where pressure is reduced as temps drop. I run my stock OR tires (on 8" wide rims) at 36-37 and there is still a slight bulge but they check fine with caulk test and wear is even and consistent. Of course the OR OEM tires are bigger than SR5, but the same principle applies.

 

That's another reason why I run them a few psi above recommended, tires usually lose about 1psi per month and 1psi per 10° drop in temp so at 32, I have three months or 30 degrees of leeway before I have to put more air in

 

I ride with 35 front and 33 rear and its smoothed out thr ride from the dealers 39 psi. No drop in mpg either.

 

Stock is stock. Jam is acceptable.

I am not stock. I periodically drive a dew-laden cinder parking lot to gauge wear at my most desired pressure, that, for me, balances performance with ride quality.

If you look at the profile on edge (so called “9:00-o’clock position”) you will see my current tire pressure under my stable load and wear mileage is perfect.

It’s a taco, play with it!

 

Why do your tires loose 1 psi/month? That is not the experience I’ve received when measured with a real gauge under similar environmental conditions of load, atmospheric conditions and temperatures

 

From day 1 I put 35 psi into stock Firestone's destination LE2. They still have 6/32 left and worn evenly.
OP, 29 is to low. Even my Prius suppose to run 32.
Depends on the tire, 34-36 psi (cold) is a sweet spot

 

My door jam placard has 32* Cold. ('17 ACLB 4x4)

 

I'm no scientist but I believe it's because the seals and rubber itself are porous and air can gradually escape. Idk the science but its true.

https://www.discounttire.com/learn/tire-pressure