Tire inflation question?

[otis24]

I replaced the OEM tires on my Dodge Grand Caravan. The tire placard on the inside of my door says 36 PSI for inflation. Do I follow this or the max. pressure guide on the tire itself? The max press. on these tires is 44 psi. What should be my guide?

 

[tripleM]

Hi Larry, the max pressure is to be use only under full load ie carrying max # of ppl or baggage, lbs etc.

I would set @ manufacturer's suggestion & then move UP incrementally from there to gain better personal wear, handling & comfort.

Since the Minivan will carry lots of things, I would move to about 36-40 PSI but would never goto max unless I was carrying a full load.

 

[GC4lunch]

Quote:

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I replaced the OEM tires on my Dodge Grand Caravan. The tire placard on the inside of my door says 36 PSI for inflation. Do I follow this or the max. pressure guide on the tire itself? The max press. on these tires is 44 psi. What should be my guide?

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Follow the placard on the inside of the door. Dodge has determined that an inflation pressure of 36 psi gives the optimum balance for ride comfort, performance, and wear for an assumed load that you will be carrying in your Caravan; automobile manufacturers spend a lot of time and effort making that determination.

Assuming that your tires are standard load (SL) tires, their load rating is based on an inflation pressure of 35 psi. (If they are reinforced, or XL, tires, the load rating is for an inflation pressureof 41 psi.) Increasing the pressure in the tire does several things: it increases the load that the tire can carry, and (for a given load) it reduces the size of the contact patch where the tire rests on the pavement. At a given tire pressure, an increased load "squishes" the tire down and enlarges the contact patch (and has other effects as well), so you may wish to increase tire pressure temporarily on those occasions when you are driving the Caravan fully loaded. The max. pressure rating on the sidewall, while really directed to the installer who is fitting the tire to the rim, is also a pressure not to exceed when inflating the tire for those extra loads. (Remember, these are cold pressures: the tire may experience much higher pressures when the tire heats up.)

The sidewalls of the tire flex with each revolution of the tire; if the tire is underinflated for the load, the sidewall flexes more than if it is properly inflated for the load. As the sidewall flexes, it generates heat through internal friction, the more it flexes, as, for instance, when it is underinflated, the more heat it generates, and faster. The "speed" ratings of tires (S, H, V, Z, etc.) are actually the speed a properly inflated and loaded new tire is more or less guaranteed to explode from its own internally generated heat. An underinflated tire also will wear out faster than a properly inflated one.

An overinflated tire, OTOH, will give a harsher ride, and will tend to wear unevenly, especially in the middle of the tread.

 

[CapriRacer]

All of the above is predicated in using the same tire size. If not, then you need to recalculate the pressure.

 

[williar]

The manuf. recommended pressure is, usually, set to give the best ride & comfort using factory-original tires. I consider it to be the minimum safe pressure and choose to run several pounds over the manuf. recommended pressure, depending on time-of-year and load.