Toyota Recommended PSI : 35 front / 33 rear

[OVERKILL]

The proof is in the results OVERKILL. I (and many other Sienna owners, ask eddy) have been able to double the life of our tires by increasing the tire pressure, which in my case has eliminated the excessive inner and outer tread wear caused by underinflation.

I don't think it's correct to call it under-inflation, which is, the tire being inflated below where it is supposed to be or perhaps below the required load carrying capacity, neither of which is accurate in describing what you experience.

This vehicle experiences undesirable tire wear characteristics at the OEM-specified pressure; at the spec level of inflation. Over-inflating the tires effectively reduces this phenomena, at the compromise of traits and characteristics that are undetermined within the sample group.

I reiterate, in addition to observed tire wear, contact patch testing will confirm that the tire pressure is appropriate for the load the tires are carrying (independent of ride comfort). Manufacturer's recommendations are a good starting point, but not the be-all-end-all when tire wear indicates otherwise.

Again, load carrying capacity is determined through the load tables, not contact patch testing. An OEM's decision as to what to go with as part of engineering looks at several key areas and may choose to compromise on areas that are easily picked-up on by a layperson to improve performance in areas that aren't.

That's why I suggested talking about this with a tire engineer (@CapriRacer) because Toyota's reasoning may go beyond just ride quality. Braking distance, emergency maneuver performance and other factors may have weighted in on their decision to spec a pressure that doesn't yield ideal wear characteristics.

 

[HowAboutThis]

not really... I have seen many with a lower pressure in the rear....

I still just do the higher of the values all around. And if it's 32 or 33 I just do about 35. Makes life easier and I doubt it matters much. When it's 40° at 7am and 80° at 5pm, you've probably added a couple few pounds accidentally anyway...

 

[Mr_Luke]

The proof is in the results OVERKILL. I (and many other Sienna owners, ask eddy) have been able to double the life of our tires by increasing the tire pressure

How much more pressure do you run in your tires?

 

[CapriRacer]

That's why I suggested talking about this with a tire engineer (@CapriRacer)

Like a Genie, I am summoned!

I try to be very careful about what words I use and how I use them so that my meaning is as clear as possible. Other people, not so much!

Here's how I see the Toyota Sienna tire wear issue:

Other similar vehicles don't have the tire wear problems that the Sienna does. That leads me to believe there is a problem with either the suspension geometry, or the steering geometry (maybe both?) Toyota would not be the first one to have such issues.

Raising the inflation pressure solves the wear problem, but I am sure it creates others, but the folks who have Sienna's are so grateful to have dealt with the wear issue, that they are very forgiving about those other issues.

Why doesn't Toyota address the tire wear issue? Redesigning a suspension and/or steering is expensive, and the first step is identifying there is a problem and getting the responsible group to admit to it. People tend not to admit to mistakes and certain corporate cultures encourage that behavior. I have experienced enough to think that Toyota is one of those!

So it isn't that the inflation spec is too low, it's that inflation pressure is being as a tool for address an issue that should be fixed another way (redesign the suspension and/or steering). But that fix is beyond the reach of the average consumer, so the consumer grabs onto whatever works.

 

[OVERKILL]

Like a Genie, I am summoned!

I try to be very careful about what words I use and how I use them so that my meaning is as clear as possible. Other people, not so much!

Here's how I see the Toyota Sienna tire wear issue:

Other similar vehicles don't have the tire wear problems that the Sienna does. That leads me to believe there is a problem with either the suspension geometry, or the steering geometry (maybe both?) Toyota would not be the first one to have such issues.

Raising the inflation pressure solves the wear problem, but I am sure it creates others, but the folks who have Sienna's are so grateful to have dealt with the wear issue, that they are very forgiving about those other issues.

Why doesn't Toyota address the tire wear issue? Redesigning a suspension and/or steering is expensive, and the first step is identifying there is a problem and getting the responsible group to admit to it. People tend not to admit to mistakes and certain corporate cultures encourage that behavior. I have experienced enough to think that Toyota is one of those!

So it isn't that the inflation spec is too low, it's that inflation pressure is being as a tool for address an issue that should be fixed another way (redesign the suspension and/or steering). But that fix is beyond the reach of the average consumer, so the consumer grabs onto whatever works.

Thank you as always! That's in-line with what my thoughts were on the subject.

My only other musing was whether Toyota had done it on purpose to make the vehicle handle a specific way, perhaps in an emergency maneuver. Reminds me a bit of the wild camber BMW was dialling in on some of their sedans, which was supposed to aide in handling under conditions that most people would never experience driving the car.

 

[930.engineering]

.
If it matters, I fully agree with both of you. If you deviate from the manufacturer's
recommendation this has to come at a price. Ride comfort is a point, (wet) traction
is another one that should be more of a concern. Over the entire life of the vehicle
when you raise tire pressure significantly it's also suspension wear. It will increase.
That I doubt someone will double tire life by just increasing tire pressure over the
manufacturer's recommendation, but I don't want to blame anyone. Biggest factor
for tire life is the driver though.
.

 

[PandaBear]

35 all the way round on my '17 Camry 2.5 per the door placard. Generally , the placard will be the same pressure for all 4 tires.

My Integra is 29 F 30 R, so not even always front is higher than rear or all 4 the same.

 

[PandaBear]

The first step is identifying there is a problem and getting the responsible group to admit to it. People tend not to admit to mistakes and certain corporate cultures encourage that behavior. I have experienced enough to think that Toyota is one of those!

Wife works for a "Japanese startup" that has been in "business" by gov funding for 20 years!

The HQ in Tokyo flat out refuse to correct any mistakes to any Japanese regulation agency or counterpart in Japan. They are willing to dump $1M worth of inventories than to admit mistakes, and when caught with mistakes by my wife's dept they say they would "send a formal apology" to us but will not fix them (because they already submit stuff to regulation there).....

From most people I've worked with dealing with Japanese politics and corp culture, "the nail who stand out must be hammered down" is real, and they would rather go down together on a sinking ship than to be tossed off the boat telling the captain the ship is sinking.


My dad's Mazda 5 has the same problem in the rear camber wearing the inner shoulder too fast, and the camber is not adjustable (-1.5 to -2.0 or so?). So..... I toss in a camber arm on each side those Mazda 3 ricer use when they lower their car, check some forums and see people usually go 5 turns from stop on the screw and be done with it. The shop said they can only do it once if they are charging only $200 labor and no fine tuning. I got very lucky that it was perfect on the dot (-1.0") by chance.

 

[PandaBear]

My only other musing was whether Toyota had done it on purpose to make the vehicle handle a specific way, perhaps in an emergency maneuver. Reminds me a bit of the wild camber BMW was dialling in on some of their sedans, which was supposed to aide in handling under conditions that most people would never experience driving the car.

Sometimes, products design have to go through so many corner case testing like you said on extreme handling for "safety" that they trade off day to day operations for those scenarios. Maybe killing 1 less people out of 1M sold vehicles is a trade off they want to make vs 40M fewer worn out tires in the landfill? Who am I to judge them if I don't own the car? If I do own the car and never drives in the snow maybe I'd rather take my chance of dying to save the tires?

 

[meep]

The sienna tire wear issue reminds me of the square-bodied vanagons in the 80s. It was a full minivan on car-sized tires. I do recall it going through tires quickly, but I don’t know the numbers. I do remember that the oem pressures were close to the sidewall max - either in the 40s or 50s, and we had a difficult time keeping anything inflated that high over a week, and with manual steering, it needed to have close to placard pressure to park it.

 

[dubber09]

Manufacturer's recommendations take into account ride comfort which translates to lower air pressure.
Personally, I run 38psi in front and 36psi in rear tires on Sportage thou KIA recommends 35psi in both.
35psi front and 33psi rear in Forte, KIA recommends 32psi in both.
Winter tires get different treatment thou mostly dependent on road conditions as we don't see extremely low temps - clear/snow.

 

[nthach]

They are going by Corvair standards. Not often is the rear lower than the front. Must be something with the weight distribution

Prius has a battery pack in the rear and a tendency to oversteer slightly from what I’ve read. It’s based off the Corolla or Yaris(C) platform but has thinner sway bars and different shocks. I run 3psi above the placard pressure but maintain the 3psi differential as specified.

 

[CharBaby]

I try to stay right around the PSI recommendation on the door jamb placard. i.e., my Altima calls for F:33/R:33.
I like a little less air in the rear myself for everyday-ness unless we're on a long journey with weight in the trunk and maybe some passengers. Then I'll up the PSI in the rear...and maybe the front too if we're traveling several hundred miles. I use the butt dyno.

 

[Spyderman24_7]

It probably wouldn't make any difference if they were all pumped up to 35 PSI.

Spot on as I take manufacturer recommendations with a grain of salt. Mine is rated for 35 front/rear, but I adjust them to 36.5 every 12 hrs to offset ambient changes. Tires are rated for around 45K miles and I get 45,001 before buying a new set, so it must be working in my favor. All joking aside, I do respect those at least interested in asking about this sort of thing as I see lots of cars where the owner clearly doesn't check anything on it and still driving like no tomorrow.

 

[JHZR2]

not really... I have seen many with a lower pressure in the rear....

I’ve seen a few with lower pressure in the rear. My Saab was like that. Others, for me specifically my RWD MB and BMW cars, use a slightly higher pressure in the rear.

 

[Hermann]

My 2008 Tacoma placard listed 32f - 29r. 2.7L 4 cyl 2WD 5-speed

If I put 32 psi in the rears, understeer was more pronounced. Tested on a high speed, long sweeping exit ramp 5 days a week. Was easy to feel the difference when I applied power in the sweeper

 

[JHZR2]

The proof is in the results OVERKILL. I (and many other Sienna owners, ask eddy) have been able to double the life of our tires by increasing the tire pressure, which in my case has eliminated the excessive inner and outer tread wear caused by underinflation.
I reiterate, in addition to observed tire wear, contact patch testing will confirm that the tire pressure is appropriate for the load the tires are carrying (independent of ride comfort). Manufacturer's recommendations are a good starting point, but not the be-all-end-all when tire wear indicates otherwise.

Same on our Odyssey. We got rid of our OE tires at 60k or more, with a huge percentage of tread left because we had been running higher pressure from the start.

 

[edyvw]

Same on our Odyssey. We got rid of our OE tires at 60k or more, with a huge percentage of tread left because we had been running higher pressure from the start.

Odyssey is a bit better than SIenna. I agree with @CapriRacer that there is a different underlying issue that is causing that (geometry, suspension, heavy front). I personally was not inflating too high as others as I had on Sienna those POS Bridgestone DriveGuard RFT tires (talking about junk). The nature of RFT is to be harsh, but Bridgestone takes that to another level. So running 42psi was really harsh, and I was hoping kind of to wear them out faster . I did though run a minimum 42psi on my 17" snow tires, and they were wearing OK, though faster then snows on my BMW or Tiguan.
But, the root of the problem is elsewhere, and Toyota being Toyota, unless they are made to do it by NHTSA, they will never admit a mistake.
Not sure about the new one considering it has a different platform and finally independent suspension in the back which greatly improves drivability, though power is abysmal.

 

[mjk1967]

I've always run lower on the 2 Avalons I've owned. 30 while warn. They just don't like 35 PSI. Just my preference