Tire pressure is 100% related to the tires that are on the car.
If the tires are not the original tires from the car, the doorcard may not be correct as far as tire pressure goes.
Inflating tires just below max PSI is not bad for the tires, so you must go by what the tires say. If the tires say 44psi and the car calls for 32, you can certainly/safely get away with bumping up tire pressures to 38-40psi without having a problem or causing irregular wear.
Getting maximum MPG is tricky. There are secrets to it, for sure, but by no means should you be running 10mpg with our tune.
Something else must be wrong(stuck open injector, spark plugs, etc.). The easy way to solve this would be to datalog the car and see what fuel trim and timing look like. From there, if the tune is fine, I would definitely look into your fuel/ignition systems for the source of the problem.
Also, to get maximum gas mileage, as keep your windows up. Having the windows down, especially on the highway will significantly reduce fuel mileage.
Dan Bailer | AmericanMuscle.com
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