Tire Pressure?

[GrayWhale]

What's a good tire pressure for a pretty loaded up van, on stock 15" tires (touring tires) for the summer and for the cold winter in the East Coast?

2000 Dodge B1500 Conversion Van w/TV top

 

[ArtW]

get a piece of chalk and make a line across the tires, then roll forward a bit
look at the chalk
worn in the middle? lower pressure
worn on the edges? increase pressure
worn evenly? stay with whatcha got

 

[SternWake]

Likely a p235/75/15XL


What is the max inflation PSI listed on the side of the tire?

35?  50psi?  42?

The max pressure is to be used at maximum loading.

Proper tire pressure is dependent on the weight they are carrying.

Too much PSI and there is less tread hitting the asphalt and traction can suffer in the wet. Also one is more likely to be able to feel every road irregularity.  Too little and the ride is softer, but the tire will heat excessively at highway speeds and wear faster.

My 30x9.5x15 tires are slightly larger than 235/75-15 and have a max inflation pressure of 50PSI.  I generally keep them in the 42 to 45 PSI range and check them before any extended period of highway driving.

 

[ccbreder]

What does the tire information placard list as proper weight and tire pressure? Find it on the right side door frame. More parts than tires are effected by over weight loads. I have always kept my cold pressure at the max shown on the tire. My weights varied, but I wanted best gasoline mileage and longest tread life. This is not a recommendation, only what I have successfully done in the past.

 

[Ballenxj]

get a piece of chalk and make a line across the tires, then roll forward a bit
look at the chalk
worn in the middle? lower pressure
worn on the edges? increase pressure
worn evenly? stay with whatcha got

The most logical advice I've seen.  If you think your weight is maxed out, or close to it, inflate close to the max pressure listed on the sidewall for starters.

 

[LowTech]

get a piece of chalk and make a line across the tires, then roll forward a bit
look at the chalk
worn in the middle? lower pressure
worn on the edges? increase pressure
worn evenly? stay with whatcha got

That's how we do it on our trucks as well.

www.DirtTrackTravelers.com

 

[Van-Tramp]

Yep, max pressure as noted on the tire.

 

[Vonbrown]

I have always inflated my tires to the recommended tire pressure and tire size listed on the decal inside drivers door post.

 

[Almost There]

I have always inflated my tires to the recommended tire pressure and tire size listed on the decal inside drivers door post.

Tire size, yes, tire pressure, the recommended is not based on what you're carrying in the van and in most cases is set for the most comfortable ride, not the pressure for tire longevity.

 

[Vonbrown]

http://www.cartalk.com/content/summer-driving-tips-6

 

[Vonbrown]

http://physics.stackexchange.com/qu...-tire-pressure-change-with-weight-of-car-load

I'm just trying to help, of course, you are free to decide for yourselves.

 

[ArtW]

Numbers posted on stickers are arbitrary, the chalk method will give you the correct inflation for your specific vehicle, with your specific load , to ensure correct contact patch and prevent tire over heating
heavier load requires more air pressure, within the limits of the tire

In fact, one of the problem leading to the Explorer's flipping problems was that Ford, having overstiffened the suspension, recomended too low an inflation for the tires
The other was that most 'loaded' explorers would be overloaded simply by putting 4 200 lb people in them, as their carrining capacity in that format was only 700 lb

 

[SternWake]

When i left Discount tire, with my LT slightly oversize tires, I noticed how much smoother they rode.


When I checked the PSI, they were what the sticker on the door said. 

32 PSI  30 PSI rear is too low for a 50 psi max inflation tire.

The door sticker is only for the original size, original load tires.

Max PSI on sidewall could easily be too high, and have too small a footprint, leading to excessive tire wear in middle and poor traction, especially in wet.

I like the chalk method.

 

[GotSmart]

Numbers posted on stickers are arbitrary, the chalk method will give you the correct inflation for your specific vehicle, with your specific load , to ensure correct contact patch and prevent tire over heating
heavier load requires more air pressure, within the limits of the tire

In fact, one of the problem leading to the Explorer's flipping problems was that Ford, having overstiffened the suspension, recomended too low an inflation for the tires
The other was that most 'loaded' explorers would be overloaded simply by putting 4 200 lb people in them, as their carrining capacity in that format was only 700 lb

That was 20 years ago.  It was the combination of a badly designed tire, mated to a poorly designed truck.  

The numbers are not arbitrary, but scientifically calculated to not make any more lawyers rich over this known problem.  If in doubt, look up the inflation information online with the vehicle or tire manufacture.   

An overloaded vehicle could lead to dangerous pressures using the chalk method. 

Also, do not buy a 90's to 2010 Explorer. 

Remember the 70's Pinto with 721's?

 

[ArtW]

I had a 91 Explorer, 4x4, 5 speed. It was a good reliable vehicle, with the factory tires, but not at the under inflated factory pressures
and the load on the vehicle doesn't increase tire pressure much, if any
That's why you increase pressure when you increase the load, to keep the correct contact patch
Doubt it? air your tires to the recommended PSI for an unloaded vehicle
load it to near it's max capacity
The tire pressure will increase very little, if any, and the contact patch will indicate under inflation

 

[Matlock]

I've recently weighted the truck using 4 individual scales so I have a readout of the weight on each tire.
I'd like to set the pressure's to a warm/hot highway PSI. What tire pressure gauge is recommended? I know some of those pencil types are really not accurate.

 

[Optimistic Paranoid]

I've recently weighted the truck using 4 individual scales so I have a readout of the weight on each tire.
I'd like to set the pressure's to a warm/hot highway PSI. What tire pressure gauge is recommended? I know some of those pencil types are really not accurate.

I really like the round Accu-Gage's by Meiser.  Some of them can be ordered from Amazon.

http://www.ghmeiser.com/

 

[Spaceman Spiff]

I agree with Vonbrown: go with the manufacturers recommendation.  If different than the original tires go to the tire manufacturer.

Tire dynamics is a very complicated subject.  Tire manufacturers go to a lot of trouble to determine correct tire pressures for a given tire-weight combination.  Tire chalking, which gives a good indication of one of the variables: side to side tire patch profile, gives little indication of the other two: front to back tire patch profile and vertical tire profile.  All three contribute to tire longevity, gas milage, traction and safety.  Additionally, chalking only give a picture of when the tire is going straight and when cold.

When you load a tire three things happen: The tire patch grows and the sides bulge (with more bulge at the contact patch) and the air pressure increases.  Static air pressure change seems to be small (< 1%, see Vonbrown's second article).  The tire patch grows, mostly in the front to back direction and the tire patch changes shape due to anticlastic flex (the center of the tread flexes up due to tire sidewall bulge).  Sidewall bulge and tire patch size are the two driving factors in tire heat; which does affect air pressure (as any NASCAR fan knows).

This doesn't even get into tire squirm, side to side deflection, puncture resistance, deflection under braking, deflection under cornering . . .

 -- Spiff

 

[steamjam1]

What's a good tire pressure for a pretty loaded up van, on stock 15" tires (touring tires) for the summer and for the cold winter in the East Coast?

2000 Dodge B1500 Conversion Van w/TV top

Is gonna depend on how loaded. I use LT235/75/15 with a "c" load range on my Ford hightop van. Its self contained so it weighs alot. I keep the tires at the max pressure recommended on the tire. Handles and feels good on the road.