Increase tire pressure to max sidewall
Reduces rolling resistance which decreases the amount of power your car needs to move.
There are mixed anecdotal reports about improvements in other properties (steering response, wet traction, and tire wear). Some folks report improvements and some report degradations.
Instructions for mod
Check tire side wall for max PSI. Inflate to that number.
At Max side wall pressure the ride comfort will go way down, you will feel the bumps more. Backing down the pressure to 44PSI (about 10% under max) is usually a good balance between MPG and ride comfort.
By increasing pressure you decrease the contact patch of the tire slightly. This makes the weight per area of contact go up, increasing traction and reducing rolling resistance. Less rolling resistance = higher MPG.
Many users have found that this mod also increased their wet and snowy traction. Cornering speeds can also go up with the higher pressure.
Note: Many service station pressure gauges are not accurate. Some people have damaged their wheels and found that their tire pressure was 5 or 10 PSI higher than they intended because of inaccurate pressure gauges. Purchasing an accurate hand held pressure gauge may be useful to check when inflating tires close to their max pressure.
|User Name||Car Make, Model, Year||Cost of Mod||Time to Perform Mod||PSI Before Mod||PSI After Mod||MPG improvement guess||Instruction Link|
|Weather Spotter||Toyota Matrix, 2006||$0||0 min (do at regular pressure check)||33.4 (32 psi)||33.9 (44 psi)||1.5% (or .5 MPG)||No ABA testing, just tank to tank averages over 2 months|
|MetroMPG||Pontiac, Firefly, 1998||$0||0||assuming 30PSI distance covered in coast down test 667ft|| Coast down distance vs PSI
20 - 569
30 - 667
40 - 678
50 - 673
60 - 686
| Percent distance change from 30 PSI
20 - 14.7%
30 - 0
40 - 1.7%
50 - 0.9%
60 - 2.9%
| Note: Coast down percentage increase may not directly translate to MPG percentage change |
Experiment: coast down distances @ various tire pressures
|trikkonceptz||Pontiac Vibe, 2004, Automatic||$0||0||32PSI||to 44PSI||1-4% (also changed driving at the same time) this helped but not sure on how much.|
|Echo-Francis||Toyota Echo 2005||$0||15 Mins||33PSI||45PSI Summer / 40PSI Winter||Not Tested.||Echo-Francis Tire Pressure|
|cbaber||Honda Civic HX, 1998||$0||5 min||30 PSI||45 PSI||~7% (3 MPG)|| Comparing tank averages over at least 3 tanks on each pressure. |
15 More PSI = 7% better MPG
Note: When testing MPG improvement the increased pressure will increase the tire radius therefore a scangauge or similar device will not display accurate efficiency until its recalibrated. A standard back to back test using the scangauge MPG output will not give reliable results
The ideal method of testing involves checking the amount of fuel used when traveling at constant speed between 2 defined locations for different tire pressures.
Problems / Consequences of mod
First off ride noise and vibrations will increase substantially.
Some users (under 20%) have reported that their tire wear becomes uneven at higher pressure, many (over 50%) report longer tire life at higher pressures. Keep an eye out for uneven tire wear.