Max Tire Pressure?
- Thread starter kmaluo
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The stock tires have a max pressure of 51 psi. My past two vehicles I've ran close to max tire pressure without any problems. The manufacturer usually recommends a lower pressure for a smoother ride and better handling characteristics. I figure I could get a few more miles a charge from slightly increased air pressures.
jmueller065
Well-known member
Has anyone done any testing on this:
Run for two weeks at 38 PSI and record average power consumption.
Run for two weeks at 50 PSI and record average power consumption.
Compare?
(I know its really hard to control for various conditions: weather, traffic, etc. but hopefully over the course of a couple of weeks things should average out.)
Run for two weeks at 38 PSI and record average power consumption.
Run for two weeks at 50 PSI and record average power consumption.
Compare?
(I know its really hard to control for various conditions: weather, traffic, etc. but hopefully over the course of a couple of weeks things should average out.)
WattsUp
Well-known member
Also, in case anyone doesn't know this, recommended PSI values should always be used with cold tires. Driving around on a tire (flexing the rubber back and fourth) heats it up, and the air inside, which increases pressure. As does exposing the tire to hot pavement. Hot tires may read a few more PSI than where you filled them, so take this into account when checking/adjusting pressure.
Also, it is not a great idea to overfill your tires, for two reasons... it creates extra stress the tire is not designed for and may lead to uneven, and ultimately, unsafe wear patterns. The typical symptom of an overfilled tire is wearing more towards the center of the tread than the edges. This is because, overfilled, the tire is slightly "bulging" down the center, where it thus wears faster.
The best thing you can do for driving efficiency is fill your tires to the recommended PSI (when cold, of course) and routinely check that they maintain that pressure.
Also, it is not a great idea to overfill your tires, for two reasons... it creates extra stress the tire is not designed for and may lead to uneven, and ultimately, unsafe wear patterns. The typical symptom of an overfilled tire is wearing more towards the center of the tread than the edges. This is because, overfilled, the tire is slightly "bulging" down the center, where it thus wears faster.
The best thing you can do for driving efficiency is fill your tires to the recommended PSI (when cold, of course) and routinely check that they maintain that pressure.
If you stay under the max pressure rated on the tire, you won't be putting undue stress on the tires, and probably won't experience uneven wear. I can't fathom how less rolling resistance wouldn't translate into greater range. Now having a slightly harsher ride, that's another story. I do agree that over inflating past the max tire pressure can lead to a slew of problems.
WattsUp
Well-known member
Sure, it is generally true that tires should have less rolling resistance with higher pressures. I was just trying to caution people to not go out and overinflate their tires for probably very little gain, if any, versus the many potential problems.
For any particular vehicle/tire combination, the vehicle manufacturer provides the correct PSI based on, among other things, vehicle weight and performance. All vehicles can benefit from low rolling resistance, so the recommended PSI should already be fairly optimal (well, at least for vehicles that the manufacturer wants to get good mileage). In any case, overinflation does't mean "simply" going past whatever the tire's maximum PSI happens to be. Just because a tire can inflated to some maximum PSI doesn't mean that it should be, or that it is even safe to do so for the given vehicle.
With the FFE, the recommended PSI is already slightly higher than with most passenger cars, most likely due to the increased weight. And, no matter what, even a few PSI can make a difference (ICE vehicles with slightly underinflated tires can suffer a measurable decrease in MPG) so, IMO, if people are going to experiment with their FFE's tire pressure, I would try something like 40 PSI first, maybe 42. Not 50.
For any particular vehicle/tire combination, the vehicle manufacturer provides the correct PSI based on, among other things, vehicle weight and performance. All vehicles can benefit from low rolling resistance, so the recommended PSI should already be fairly optimal (well, at least for vehicles that the manufacturer wants to get good mileage). In any case, overinflation does't mean "simply" going past whatever the tire's maximum PSI happens to be. Just because a tire can inflated to some maximum PSI doesn't mean that it should be, or that it is even safe to do so for the given vehicle.
With the FFE, the recommended PSI is already slightly higher than with most passenger cars, most likely due to the increased weight. And, no matter what, even a few PSI can make a difference (ICE vehicles with slightly underinflated tires can suffer a measurable decrease in MPG) so, IMO, if people are going to experiment with their FFE's tire pressure, I would try something like 40 PSI first, maybe 42. Not 50.
jmueller065
Well-known member
More data points, although from a different, much less efficient, vehicle:
On "heavy" trucks (like 3/4 and 1 ton ones like our F-350) you actually adjust the tire pressure (at least the rears) based on the load. Normally our truck runs ~60 PSI in the rears when empty, but hook up our 5th wheel and I have to pump them up to 80 PSI.
I drove it a while with 80 PSI in the rears with no load on the truck--it doesn't take much time to get the center section of the tire bald (it also depends on the rubber formulation some tires are softer than others).
On "heavy" trucks (like 3/4 and 1 ton ones like our F-350) you actually adjust the tire pressure (at least the rears) based on the load. Normally our truck runs ~60 PSI in the rears when empty, but hook up our 5th wheel and I have to pump them up to 80 PSI.
I drove it a while with 80 PSI in the rears with no load on the truck--it doesn't take much time to get the center section of the tire bald (it also depends on the rubber formulation some tires are softer than others).
DavidJohnson
Active member
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- Feb 26, 2013
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- 38
I didn't see much discussion about traction in this thread. My wife and I used to race autocross and we adjusted our tire pressures based on traction. We used two tools, a thermometer and white shoe polish on a section of the tread and wall, to make our adjustments. As little as 5 psi can really change the contact patch (in square inches) between the tire and the road and either help or hurt your traction. I would be hesitant to change the pressure by more than 5 psi because you don't know how the traction (dry or wet) will be affected. It may be fine in dry weather and then a quick shower happens and the car may not have the traction you think it has. I wouldn't suggest that you change it much at all because I believe you're unknowingly (or knowingly 
) increasing the risk of an accident. Why take the chance for a few cents of electricity? If you're really interested, they sell digital contact thermometers for under $100 that will give the temperature profile across the width of the tire. Higher temps will indicate more 'work' or traction (and wear). You could gradually increase the pressure and monitor the temps to judge when to stop. Just my thoughts.
) increasing the risk of an accident. Why take the chance for a few cents of electricity? If you're really interested, they sell digital contact thermometers for under $100 that will give the temperature profile across the width of the tire. Higher temps will indicate more 'work' or traction (and wear). You could gradually increase the pressure and monitor the temps to judge when to stop. Just my thoughts.Agreed: good traction counts far more than a bit of electricity (or even a couple more miles range).
In this car especially, the tires tend to spin a bit when adding power in a turn (at least at low speed), even with the normal 38 psi. Higher pressure may make that even worse.
In this car especially, the tires tend to spin a bit when adding power in a turn (at least at low speed), even with the normal 38 psi. Higher pressure may make that even worse.
