Ok, here's some ideas ive been teetering with for the last few days,
considering the snow me having to let air out of my tires for saferty.. lol
Does anyone know the formula that can calculate tire height vs trip odometer mileage..
one thing that can cause your odometer to really rack up the miles is smaller tires(more spins per mile)
so having bigger/taller tires, ect can cause your mpg numbers to go down due to the less spins needed per mile..
yet adding psi will increase your mpg by a certain said amount( this varies by car)
so by adding psi are you not really getting exact mileage unless you've thrown in a math formula to account for higher tire height?
meaning that you might be getting even better mileage(providing you have a control mpg using stock psi/height that matches your car's computer's recognition as what a mile is) than you're odometer says you are..
wouldnt you think on some cars that this unaccounted for error could actually be a 1-2mpg difference, well I would need the formula to even hypothesize this, someone here has to know it...
Well, that issue can be done by many gear calculators. Height is only useful for determining circumference. Get the circumference and you have the distance the car will go with one tire revolution. You can feed size, diameter, or revolutions per mile into this gear calculator: http://f-body.org/gears
Also feed in your diferential and at least one transmission gear and you'll get your answer.
Trie diameter doesn't hange much with air pressure. Unlike a ballon, it has steel cords in the tread that don't stertch much.
yea.. well an inch on my tires on my car is the difference from 29psi to38psi, I mean how tall the tire is while on the car.. and could potentially mean alot in terms of long term results measuring mpg, to the point where this has its own calculator
all you can be doing is giving your self a higher mpg readout and more accurate.. whats wrong with that?
The easiest way to measure this is to use a ruler or tape measure and measure the height of the tire from the ground to the bottom of the rim at it's lowest point. While you're doing that, let out ten psi and compare the change. Use that measurement to calculate effective diameter/circumference. It'll be different for front and rear tires since they carry different ammounts of weight.
That doesn't work because the tire CIRCUMFERENCE is NOT changing with different air pressure only the about of SAG in the sidewall on the bottom of the tire. You still travel the exact same distance per revolution no matter what the tire pressure.
Now for some bad news . . . apparently the tire rolling resistance increases with taller tires so putting taller tires may lower the engine RPM and effectively change the final gear ratio and Odometer reading but it also apparently increases rolling resistance too.