Best tire pressure for fuel economy = 38?

[Booneabal]

I have an 2LT RS and about a month ago one of the tires had a slow leak and I ended up pumping up all the tires to about 38psi cool. I noticed that I got a slightly stiffer ride (nice) and my fuel economy jumped 2mpg to a solid 22 every time.
Since I got the car serviced they lowered the tires to 36 psi and my fuel economy is now back to 18.9-19.7 range all the time.
I plan to go back to the 38 psi because the tires are rated for 40 so I don't think its an issue.

Anyone have any experience with this?

[wbdinger]

For fuel milage you should run the tires at the maximum rated pressure. 40-50 what ever the tire says on the sidewall.

[philipdistefano]

My tire pressure is at like 34 for all tires. Is this too low?

[Booneabal]

Originally Posted by philipdistefano

My tire pressure is at like 34 for all tires. Is this too low?

I think so, there is a sticker on the inside of the driver side door that gives you the recommended pressure. At 34 your ride is probably really soft and you are wasting alot of power to the tires.

[wbdinger]

also @ 34psi the tire will wear the inner/outer edges as the contact patch in the middle is not touching the road. especially on these wide tires

[mtcwby]

Originally Posted by wbdinger

also @ 34psi the tire will wear the inner/outer edges as the contact patch in the middle is not touching the road. especially on these wide tires

Same thing, if you inflate over 36 psi you will be wearing the centers of the tires. There is a reason GM states 36psi. It is because they have figured out that with what the car weighs, 36 psi is the perfect pressure to get maximum tread contact to the ground.

[camarowa]

36 psi is recommended by gm, during spirited driving pressure will increase a bit to 38-40psi.

[PfadtRacing]

hey guys. This is an interesting topic. I think in order to make fair comparisons, we would be talking about rolling road tire pressure (or HOT), as opposed to cold set pressure. There are MANY factors to take into account for tire pressure rate increase,(ambient temps (kinda), alignment, suspension upgrades, passengers, fuel load, etc)so really, I'd be interested to see what the pressures are HOT. This should give a better baseline.

Maybe there should be a fuel economy thread stating tire pressures (hot), and appropriate supporting factors. This is interesting to see what people find.

[ron10]

36 pounds is what you should put in the tires.that is why the sticker says "cold tire pressure".factory knows the tire presure will increase when the tires get hot.

[PfadtRacing]

Hi ron10,

I think a consideration needs to be made for GM and the fact that they are supplying Camaros to a wide range of environments with varying ambient temps, among other factors. Final tire pressures always vary from one car's set up to the next (given a different set of variables). Starting with 36 is the recommended setting, for the best average final tire pressure, but isn't necessarily tailored to everyones specific use. Drivers will see different hot results depending on what they are doing (type of driving, average speeds, hard cornering etc.) and the factors listed above. This is why when posting results about fuel economy vs. tire pressure, it is best to talk about it at the hot pressure, since you do not drive on cold tires for very long. Its also important to note that all four tires will not always increase to the same pressures.

[bono83]

Run the FACTORY recommended pressure. One of the biggest goals for car manufactures is to get the best MPG possible. There are many reasons (MPG, tire wear, traction, handling, ride quality, etc.) that are factored in and considered during the design and testing of a car and tire to arrive at the recommended pressures. Max pressure on the sidewalls is for major payloads like all seats filled with passengers, the truck full with cargo, and maybe a trailer attached.

[2ndgenz28]

Originally Posted by bono83

Run the FACTORY recommended pressure. One of the biggest goals for car manufactures is to get the best MPG possible.

If that were so he wouldn't see a MPG increase, the rec psi on the door is for ride comfort first, MPG 2nd.

Hence the stiffer ride but better MPG he see's

why all those ford suv's rolled over, they wanted folks to use 28 for a nice ride, but in a panic manuver you were screwed.

[rmnc3r]

This topic comes up frequently in MC forums. Most seem to run at max recommended pressure that is on the sidewall, claiming better handling and tire life. With all due respect to 'recommended' pressures, GM, and by extension, their (tire) suppliers are in the business to SELL stuff. THAT being the case, the sooner something wears out, the better for them. In many cases, the buyer will opt to replace with the same brand/item that came as OE.
I run mine at 41-42, just a little more than recommended and a little less than
Max Rated. No empirical evidence to support or refute, just a little considered reasoning.

[2ndgenz28]

Originally Posted by mtcwby

Same thing, if you inflate over 36 psi you will be wearing the centers of the tires.

if the tire says 40 max, it will not be over infalted and wear out the center faster unless your over 40.

Most good performance tires are rated to 40-50 psi with NO deformation.

Only beyond the max can that happen.

Why its call the max, beyond that it will ballon.