Tire Pressure - Pros and Cons?

Question

Okay, so I've heard that in order to get the best gas mileage on my car, I should keep my tires "properly inflated", which for me, is 32 psi on the front and 29 psi on the back (or maybe reversed - I forgot lol). My dad says not to pump them up to that much, but he won't really say why.

So are there any reasons why it would be good to not keep them properly inflated? Is there any truth behind what my dad is saying, or is that just a common myth that hasn't publicly been really debunked? :/

Oh, and it's a 2003 Mitsubisih Eclipse (in steel blue :D)

Answer 1

Regardless of what the other young pups say, you dad knows what he's talking about and he's NOT telling you to run them when they are truely underinflated for the load they are carrying. If you look on the side of the tire, somewhere close to the rim it'll say something like "Maximum load 1,200 lbs at 35 psi" for example. That means that when the tire is aired up to 35 psi (pounds per square inch of air pressure), the tire can safely carry 1,200 pounds at normal speeds without worry of failure. If that tire is only supporting 600 pounds, then 35 psi is considered over-inflated. At that lighter load, the tire may only need 24 pounds to safely carry that load. However, turn around and put 1,200 pounds of load back on it and at 24 psi, it's severely under-inflated and will likely overheat and blow out and that possibility increases as your speed increases.

Contrary to what one gentleman said, the air pressure in a warm tire increases over that of cold and in cold weather, the pressure decreases. What do you think makes hot air balloons rise? They don't call them hot air for nothing. Hot air expands and when confined inside of a tire, the result is increased pressure. It's a good idea to check the pressure in the fall before really cold weather sets in. Over-inflating a tire will have a tendency to wear the center of the tire and under the outsides as previously mentioned. Go by what the sticker on your car's door jamb says or look in the manual for varying loads. If you have a small car and only you in it, you can go on the light side of recommendations but if you have 5 of your fat friends with you, better go with the higher recommended pressures. Also, the faster you go, the higher the pressure needs to be. If you're running 85 mph in Montana, better up the pressure to the maximum recommended.

Answer 2

Over inflation will flex the tire too tight and wear out the center portion, underinflation causes the sides to wear out. Control is also dependent on proper inflation. However under inflated tires have less resistance to heat and can blow out..it is a friction with the road issue and the tire not having a high heat range. POW--it blows out at 65 and off into the woods you go !! People very seldom think to ask about load and heat ranges of the tires they are buying. Overloaded tires with improper inflation can also blow out. Stick with the recommendations--and do your inflation cold--noy after the car has been driven any amount of time..the reading will not be correct due to heat. remember the friction I mentioned?? That heats up tires just by the nature of contact with the road as you roll along. The whole ownership and driving thing is an adult, mature attitude and understanding the hi tech equipment of today. Your dad may be stuck in the 50s when steel belts did not exist. Today's tires are complex construction with a mix of hi grade rubber products. Most people are looking for a bargain when they buy anythng for their car--you get what you pay for.No way 4 tires for 99 dollars will be a bargain in safe operation and long life.

Answer 3

Well the other guy is not correct to put it simply. Pure Nitrogen does not contract and expand like air does. For example if they inflated the tires with nitrogen to 36 psi and there are no leaks in the new tire, in theory the tire would not need any air/nitrogen until it wore out, because nitrogen does not expand and contract like air with varying outside temperatures. On the other hand we have air say it is 50 degrees out when they aired up the tires to 36 psi, well on a hot day and you have been going down the road and the tires are warm now that pressure might be as high as 45 psi (overinflated and you added no air) this is due to expansion, it goes the opposite way for real cold days say it was now 10 degrees out side the pressure in the tires would now be 26 psi (under-inflated). Nitrogen filled tires do cost you though ($$$) and many gas stations offer free air, but this requires a little effort by you to air the tires when needed. Hope this helps you make a decision.

Answer 4

Follow the auto manufacturer's specifications. That will maximize your ride, handling, vehicle performance and mileage. It will also keep the tires from wearing out prematurely. I'm not sure which manufacturer recommends 32 pounds in front and 29 out back, but if that's what is on the placard that's on the door jamb or glove box, I'd stick with it.

Make sure your tires are cool when you check the air pressure and check them frequently. Gas mileage with properly inflated tires is more than 20% improved over underinflated tires while tire life is shortened by as much as 50% when they are over inflated.

Good luck!

Answer 5

Keep them inflated at the recommended pressure.

Too much tire pressure may have less rolling resistance, but it is more prone to punctures. The ride quality may also be more stiff. The wear of the tire may be concentrated to the center. The contact patch will primarily be in the center, so say goodbye to cornering grip.

Too little tire pressure may be less prone to punctures and have a better ride qualtiy, but it has more rolling resistance and the handling may feel wobbly and loose......

Answer 6

35lbs is the average for most tires. Reasoning for raising and lowering is sometimes needed. If you plan on going on an extra long interstate ride where speeds can reach 85mph for extended periods of time you want to go up to 40lbs even 45lbs... Heat buildup actually causes presure to decrease, likewise in the winter (Cold Weather) it will expand. That might be where your dad is getting the 32/29 theory... Heavy loads on pickups really need a few extra pounds in the tires.

Answer 7

tires companies spend alot of money researching the best air pressure for their products...
why wouldn't you believe what the tire says and keep your tires at that pressure..
less friction your tires produce the less gas your motor is going to burn to give you the speed you want..
low air or too much pressure eat more gas and causes the tire to wear out faster...
if your dad says different... then he needs education on the subject

Answer 8

I would ask him why he says it. Otherwise keep them properly inflated. If it is cold out don't inflate them to maximum, or when it warms up the tires will expand. -s