Fuel Efficient Inflation?

[HighwayRanger]

Hello again all,

I have an '04 Honda Pilot with OEM mud/snow tires. The max air pressure on the sidewall is 44psi. What would you think would be best in order to maximize mpg? I always thought that it should be higher rather than lower, but am not sure. Perhaps about 38?

 

[XS650]

To answer your question as it was written.

As high as you are willing to go if you are optimizing mileage at the expense of other things.

You probably don't want to do that.

As you increase tire pressure you decrease rolling resistance.

There are diminishing returns as pressure increases. Increasing your pressure from 32 to 36 psi will make a bigger difference than increasing it from 36 to 40.5 psi and you get an even smaller gain going from 40.5 to 45.6 psi. (each increase was 12.5%).

38 is probably a good compromise. You will loose a bit of ride comfort and your tires may wear more in the center, but nothing should be too wierd.

 

[JHZR2]

There are folks in the "hypermiling" groups that inflate their tires to max sidewall or above. We of course do not advocate going above max sidewall pressure.

My saab is specced for 41/38, doesnt ride like a buckboard, nd gets great mileage, likely because the spec inflation pressure is so high. My BMW is rated for 28/32, and at 30/34, its already riding rough.

Given the issues and problems with riding with low pressure, I prefr to pressure up. What level you do it to is really up to you and up to the suspension design. Id look for a value below the sidewall spec, where the vehicle just barely doesnt ride like a buckboard. Look in the archives, but IIRC, CapriRacer said 5 (may be mistaken) was a good overage beyond placcard spec...

JMH

 

[mechtech2]

Better high than low for tire life, gas mileage, and wet weather grip.

 

[benjamming]

JHZR2,

CapriRacer had said 3-5 psi above and then check the status of everything.

 

[eljefino]

too high will beat on your ball joints, strut mounts and everything else.

 

[Quattro Pete]

Originally Posted By: eljefino
too high will beat on your ball joints, strut mounts and everything else.

Exactly. In which case whatever you save on gas, you'll end up spending on early component replacement.

 

[JHZR2]

but if youre trying to get good fuel economy, the combination of higher pressure with lower speeds driven will negate the W&T issue...

JMH

 

[dailydriver]

Originally Posted By: Quattro Pete
Originally Posted By: eljefino
too high will beat on your ball joints, strut mounts and everything else.

Exactly. In which case whatever you save on gas, you'll end up spending on early component replacement.


As well as cord your centers while the rest of the tire is perfectly fine.
I would have to save A LOT of fuel $$$ in order to justify even one new tire on my ride (minimum of $150.00 on the car).

 

[CapriRacer]

Something to keep in mind:

The footprint of a radial tires are relatively insensitive to pressure - the operative word here being "relatively" - meaning that small increases (or decreases) in pressure have minor changes in the footprint - and therefore, the wear.

My experience has been that increasing the pressure stiffens the tire faster than the change in footprint shape changes, so the tires will not wear faster in the center (or the shoulder) compared to the resistance to wear of the stiffer tire.

BTW, what I have seen for increases in forces generated by increasing pressures in tires says that within the small values we should be playing with (3 to 5 psi), the ride quality only degrades slightly - and this would apply to component durability as well. If you are going to have suspension component failures, it's probably not due to the tire pressure.