Celica Forums Install Guides and Technical Articles Suspension, Wheels, and Brakes Guides [WHEELS] Tire Pressure - What PSI Should I Use?

How Much Tire Pressure Should I Use?

You hear a lot about performance parts on the web, but the most important part of your whole car is the tires. Reeves Calloway likes to quote that "every component in a car is in place to make the tires work better... driver included" This is very true.

"MAX PSI: ##" is usually written on the side of your tire - where, "##" is the Pounds per Square Inch (PSI) that the manufacture recommends you put into your tires.

The correct way to fill your tires is to use an air compressor (at your gas station for example), fill to a few pounds just above MAX PSI, then check the pressure and release some of the air until it is exactly at "MAX PSI".

For performance street tires you should inflate your tires to the specification imprinted on the side of your tires when your tires are cold (unless noted). This is called CTP, Cold Tire Pressure. Drive to the nearest service station or use an air compressor at home to inflate your tires.

Your air pressure gauge will always show a higher pressure than normal if you check a HOT tire.

By having your tires under inflated, you may be loosing on gas mileage, causing more pollution and wearing your tires out faster and possibly unevenly...

By having your tires over inflated, you may be wearing them down more quickly and are putting yourself at risk of a traffic accident since your stopping distance will be reduced due to the over-inflated tires not being able to grasp the road as well.

The average pressure that is printed on the wall of your tire for a standard automobile is between 25 PSI and 45 PSI - CHECK WHAT YOUR TIRE'S RECOMMENDED PSI SHOULD BE SET TO. If you cannot read what is written on one tire, check another that is on your car - 99.9% chance that all the tires on your car are the same (as they should be).


The "Donut" Spare Is located in your trunk next to the "joke" jack, make sure it's got air or you are dragging it along with you for no reason. It's good for 50 miles per hour max for 50 miles (ideal), surely they can go for longer distances but they are not intended for use until you can "afford" to buy a new tire.

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Some racers like to relieve 5 to 8 lbs of PSI from the tires where the engine gives most torque (FWD or RWD) to make them more "STICKY" during take-off - However, this works just fine for the track, but for daily driving, you should always inflate to manufacturer's recommended PSI.

An informal study by students at Carnegie Mellon University [cmu.edu] found that the majority of cars on U.S. roads are operating on tires inflated to only 80 percent of capacity. According to the website, http://www.fueleconomy.gov, inflating tires to their proper pressure can improve mileage by about 3.3 percent, whereas leaving them under-inflated can lower mileage by 0.4 percent for every one PSI drop in pressure of all four tires.

Besides saving fuel and money and minimizing emissions, properly inflated tires are safer and less likely to fail at high speeds. Under-inflated tires make for longer stopping distances and will skid longer on wet surfaces. Analysts point to under-inflated tires as a likely cause of many SUV rollover accidents. Properly inflated tires also wear more evenly and will last longer accordingly.

When filling your tires with an air compressor such as the ones found at gas stations - its ALWAYS good practice to shoot the first bits of air out (away from yourself).

This will release any water that may have formed in the air compressor while it was waiting for use.

if you get enough water into your tires, they may become uneven because that water will make them unbalanced.

Also, if you live in a place that gets snow/ice, that water will form into ice inside your tires and when you drive, it will make knocking noises until its all melted - and then will make sloshing noises after that (your local wheel shop can remove the water from your tires for a small fee)

Want to learn more about your tires? Check out the article on Tire Rotation...
https://celicahobby.com/forums/ubbthreads.php/topics/23762/WHEELS-Tires-Rotation-FAQ.html