boebr1
Full Access Member
Ok... going to try to make this as simple as I can...
So you just put bigger tires on and you tried to figure out you gas mileage and it looks exponentially terrible. This formula will give you the miles you really drove.
new tire height divided by old tire height then take your odometer miles and multiply it by the factor you got in your division.
Example: my new tires are 235/85r16 (31.728" tall).
old tires are 225/75r16 (29.287").
31.728 divided by 29.287 = 1.0833
now... pretend here... try to follow me:
Say on my stock tires, I used 16.66 gallons to drive 300 miles, that is 18 MPG...
Now say on my new tires, I rack up 300 miles, but I used 18 gallons.... that suggests that my MPG went down to 16.6...
Still with me? Take your odometer reading of 300 miles and multiply it by the factor from the first step, 1.0833 on this example...
this gives you your actual distance traveled. Which would be 324.99 miles... divide that by the 18 gallons, and you would see that your mileage would have actually gone up to 18.055mpg.
These gallons numbers are fictional as I can't afford to fill my tank twice in a row lately.
If you have changed your tire size but not your gears, and you haven't had your computer reprogrammed for the new size because you like your speedometer to be more accurate (as in my case), then this is what you do to calculate your actual MPG or kpg.
So you just put bigger tires on and you tried to figure out you gas mileage and it looks exponentially terrible. This formula will give you the miles you really drove.
new tire height divided by old tire height then take your odometer miles and multiply it by the factor you got in your division.
Example: my new tires are 235/85r16 (31.728" tall).
old tires are 225/75r16 (29.287").
31.728 divided by 29.287 = 1.0833
now... pretend here... try to follow me:
Say on my stock tires, I used 16.66 gallons to drive 300 miles, that is 18 MPG...
Now say on my new tires, I rack up 300 miles, but I used 18 gallons.... that suggests that my MPG went down to 16.6...
Still with me? Take your odometer reading of 300 miles and multiply it by the factor from the first step, 1.0833 on this example...
this gives you your actual distance traveled. Which would be 324.99 miles... divide that by the 18 gallons, and you would see that your mileage would have actually gone up to 18.055mpg.
These gallons numbers are fictional as I can't afford to fill my tank twice in a row lately.
If you have changed your tire size but not your gears, and you haven't had your computer reprogrammed for the new size because you like your speedometer to be more accurate (as in my case), then this is what you do to calculate your actual MPG or kpg.
