Toyota Sienna Forum - siennachat.com banner

1 - 20 of 22 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter #1
Going on a road trip and likely will be doing straight 10 hr drive with some breaks.

2016 Sienna Limited edition tires show 51 as Max PSI but I have front at 38 and rear tires at 37 to allow any leeway for air expansion due to heat.

Is this sufficient or is it advisable to inflate until 40 PSI?

Regards
 

·
Registered
Joined
·
583 Posts
Max pressure is for when you are loaded up with weight. 6 people. The dog and trunk is full. haha. Then I would set the tire pressure up at 51PSI. Again this is max. If you run 51PSI and only you in the vehicle it will ride rough.
So the answer is how much weight are you hauling on this road trip? You will get a bunch of opinions on this. Tire pressure is set when cold. They take in effect of expansion.
 

·
Registered
Joined
·
22 Posts
Discussion Starter #3
2 adults and 2 kids and 4 large luggages(say about 200lb total) and knick·knacks so probably loaded but not to Max.
 

·
Super Moderator
Joined
·
5,019 Posts
The MAX PRESSURE shown on tires is what the tire carcass can stand before you risk doing damage.

The Vehicle Recommended pressure is stated on the placard on the B-Pillar, Drivers door. On my van it states 36 lbs. If you go to the tire mfgrs web site they often publish a chart showing load rating vs inflation pressure. It's somewhat linear (maybe going up 10-15 lbs carrying capacity per 1 psi inflation additional). Under normal conditions, I inflate cold to around 37-38. I find that helps promote even wear across the treadface. I up it 1-2 further when loaded up, but usually no more than 40 psi absolute max. Max axle rating on the van is like 3200 lbs. Your tires at 39 psi is way over the need.

Should you go more? An argument can be made that a tire has to give a bit on potholes, or you greatly increase the risk of a blowout, belt damage, wheel damage, tread crown wear, etc. I see no need to ever go much over 40 psi, but that's me...
 

·
Registered
Joined
·
297 Posts
I just set it to what is indicated on the placard on the b pilled which states 35 psi (cold) for my 2020 limited. We are currently on a trip (10 hrs) and the van rides fine are the stated 35 psi. As you drive the tires heat up and increases in PSI. During the 10 hour trip in 90+ temp, the pressure actually increase to about 39 psi on my van from the 35 psi cold pressure.
 

·
Registered
Joined
·
24 Posts
I recommend 42 PSI cold (after not driving it for several hours) all around. Max PSI is the max cold tire pressure. It can handle much more than 51 PSI, but there is a margin of safety built into that rating.

I run 42 PSI on my minivan (18" wheel), 44 PSI / 46 PSI rear in my SUV (23" wheel) and 42 PSI all around on my Panamera (21" wheel).

You will get slightly better gas mileage, smooth ride on good roads and even tire wear. When I was below 40 PSI, I would get uneven outer tire wear in the front.
 

·
Registered
Joined
·
872 Posts
This is a situation where you are the operating engineer.

Are you looking for a bit of fuel economy, versus safety? You're OK with the psi listed in the driver's door. Don't go below, and don't go too far above the specified psi,and you'll be OK.

A question to ask: how accurate is your tire-pressure gauge? I have 3, and they vary by about 25%. So beware.
 

·
Registered
Joined
·
33 Posts
i may be doing it wrong but i run the rears at 35 psi and the front at 45. it could just be the old tires on the van but the front tires just look like they are bulging a bit too much at 35-40 psi, at 45 psi they look just fine.
 

·
Super Moderator
Joined
·
5,019 Posts
You could get away with that on a FWD van. If you have AWD, you are beating the heck out of the electromagnetic clutch to have that large a difference in effective rolling diameter. A very bad practice.

Some full time AWD systems (Subaru comes to mind) do have a slightly staggered inflation (typically 2 psi greater front than rear) as a way to balance weight on the axle and tire rolling diameter to ensure uniform stress on the system. Toyota calls for zero difference front to rear. I'm going to assume they have a clue, and follow that recommendation.

Racers sometimes run the rear axle a bit soft to reduce the tendency to oversteer. You can balance a vehicle's polar rotation by softening the rear, but I doubt that's much of a concern with a minivan!
 

·
Registered
Joined
·
23 Posts
Going on a road trip and likely will be doing straight 10 hr drive with some breaks.\
2016 Sienna Limited edition tires show 51 as Max PSI but I have front at 38 and rear tires at 37 to allow any leeway for air expansion due to heat.
Is this sufficient or is it advisable to inflate until 40 PSI?
Regards
Your tires are not made only for Siennas, they also work for other cars. In other appliations 51 PSI may be appropriate, but it is not for a Sienna. What you need to do is open your driver side door and there is a sticker there with the recommended tire pressure. That is what you should use. It also makes no difference if you are on a long or short trip. The important thing to remember is to measure the tire pressure when the tires are cold. The recommended pressure on the sticker already accounts for pressure increases when the tires heat up. If you go much higher you risk uneven tire wear. When you go too high the center of the tire will wear faster than the rest of the tire. Going higher might eek out a fraction of a MPG more, but ride will suffer and your car may not handle as expected. I would follow the manufacturers recommended tire pressure.
 

·
Registered
Joined
·
33 Posts
im gonna have to go out and measure the tires now because with the rears at 35 and the front at 45 they look exactly the same. my van is fwd and im really starting to think i need some new tires cuz with both front and rear at 35 the front tires look low on air while the rear look normal.
 

·
Registered
Joined
·
23 Posts
im gonna have to go out and measure the tires now because with the rears at 35 and the front at 45 they look exactly the same. my van is fwd and im really starting to think i need some new tires cuz with both front and rear at 35 the front tires look low on air while the rear look normal.
Running pressures much different than what is recommended will alter your car's handling. By running higher front tire pressure than recommended, your car will understeer more than the car would at the recommended tire pressure.
 

·
Registered
Joined
·
33 Posts
so are the front tires supposed to look like they are bulging out as if they are low on air? or do tires just do that as they get older?
 

·
Registered
Joined
·
23 Posts
so are the front tires supposed to look like they are bulging out as if they are low on air? or do tires just do that as they get older?
Tires should not change their shape as they get older. If they do, that is a sign of cord damage which is really bad as that would make your tires unsafe. Fill your tires to the recommended cold tire pressure on the B pillar and you will be fine. Don't worry if it looks a bit bulgy.
 

·
Super Moderator
Joined
·
5,019 Posts
You can't tell a radial tire's inflation pressure by how they look. Over a wide range they look pretty much the same.

Al_NYC is telling you the same thing I told you. I couched it in terms of reduced tendency towards oversteer, while he stated it as an increased tendency towards understeer. They imply the same thing. You are messing with the vehicles handling. Stop trying to make them look like some ideal shape, and pay attention to what Toyota is telling you on the placard, and in your owners manual. Bump them up a bit over the recommended pressure if you feel you must. But keep them close to the same unless you have a specific objective in mind, and understand the potential outcome.
 

·
Registered
Joined
·
33 Posts
i cant tell its pressure by looking at it, that is correct. i can however tell it "looks" like its low, and generally when a tire looks like that i put air in it, im 33 years old, this is the 5th car ive owned in my life and none of them have ever had tires that are supposed to look like they are bulging out and are low on air. ive always run my tires as you guys have said on all previous cars, look at the sticker and keep it there +/- 2-3 psi or so. this is the first time ive ever far exceeded that but its also the first time ive ever seen a properly inflated tire look like its low before.

i trust you guys, if they are just supposed to look like that on my van then so be it, ill lower the pressure back down to 35 ish and ignore it. thanks for helping me with this, i could have been ruining my car or putting myself in more danger than necessary simply over my own intuition. i think im reaching that age where i begin to trust my intuition a little too much and am too reluctant to admit being wrong and too slow to accept changes. not every cars tires can/should look the same, that seems simple enough to swallow.
 

·
Super Moderator
Joined
·
5,019 Posts
I understand. I've looked at the sidewalls on our Sienna too at times and thought that they look low, but the gauge says otherwise. It's a heavy vehicle, but looks can be very deceiving.

The rule is COLD inflation pressure. Of course, 'cold' is a relative thing. It varies by season and situation. For example, my garage might maintain 40' F when it's near 0' F outside. I'll adjust the pressure uniformly up a psi or two to compensate. Also be careful outside in the summer. The tires that are hot from direct exposure to the sun will read several psi higher than the shady side.

I have 5 Accutire gauges, and they all read within a pound of each other. More consistent than the Slime gauges that I bought years ago. I eventually tossed the Slimes, and bought 4 more Accutire units to replace them. Each vehicle has one in the glove box, and I have one in the garage. Plus, they are in decent agreement with the TPMS readings I get from my Autel TS508, so I trust the total measurement system.

As an engineer, I'm data driven. My gut (intuition) is generally pretty good too, but I don't let my head override well presented data.
 

·
Registered
2015 Sienna SE
Joined
·
72 Posts
Whether you're running your tires at 40+ psi or the recommended factory 35 psi, unless you're racing with these vans at super high speeds around corners or on the freeway cutting in and out of traffic all you're going to feel is less resistance when your tires are spinning. You're not going to feel the oversteering/understeering these guys are talking about. Even if you do because you're an aggressive driver, your vehicle safety electronics will cut power as soon as it detects any tire slippage anyway. Typical I've seen is around 51 max psi on 99V rated tires. I wouldn't run 45 psi either though, I have mine at 40-42 psi all the way around and drives just fine. Once my current set of Pirelli P7000 wears out in a year or two here, I'll be bumping up to 103 or 105V rated tires.
 
1 - 20 of 22 Posts
Top