Don't Forget to Figure Tire Size When Calculating MPG!
#1
Don't Forget to Figure Tire Size When Calculating MPG!
I've witnessed alot of posts on here from guys talking about their gas mileage (mpg), but I rarely see where they take into consideration their tire size on their mpg calculation.
Your odometer was calculated at the factory for your factory tires and if you change your tire size, your odometer will not be accurate.
Case in point; my '96 SLT came from the factory with 225/75/16 which gives me a circumference of 28.75 inches [((width*aspect ratio)/26.5)*2+wheel diameter]. However, when I changed my tire to a 265/75/16, the increase in width, led to an increase in sidewall height of 1.25 inches due to the constant aspect ratio of 75%, which increased my circumference to 31 inches or 8%. Therefore, I am covering 8% more miles than my odometer is showing.
So don't forget to add/subtract your tire difference to your mpg.
BTW...I'm getting 14.4 mpg (before adding the 8%) and 15.5 mpg (after adding the 8%), with a 13 year old 5.9l 360!
Your odometer was calculated at the factory for your factory tires and if you change your tire size, your odometer will not be accurate.
Case in point; my '96 SLT came from the factory with 225/75/16 which gives me a circumference of 28.75 inches [((width*aspect ratio)/26.5)*2+wheel diameter]. However, when I changed my tire to a 265/75/16, the increase in width, led to an increase in sidewall height of 1.25 inches due to the constant aspect ratio of 75%, which increased my circumference to 31 inches or 8%. Therefore, I am covering 8% more miles than my odometer is showing.
So don't forget to add/subtract your tire difference to your mpg.
BTW...I'm getting 14.4 mpg (before adding the 8%) and 15.5 mpg (after adding the 8%), with a 13 year old 5.9l 360!
#3
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#7
and also take into consideration that the truck may have came with 245/75/16(factory) like mine and but the door said 225/75/16.. belive me ive known the truck since it had about 20thousand miles.... and i got it with 42,000 with the org tires
just throwing that out there alot of these truck came with bigger tires than what the door said
just throwing that out there alot of these truck came with bigger tires than what the door said
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#9
The gears will help you move larger tires, obviously, but they are completely independent from your speed.
The trucks can't adjust for tire size. How is it supposed to "detect" the size of the tire? My SC 3815 said the truck was calibrated for 245/75R16 tires even though it came with 265/75R16 tires from the factory. If you have larger, oversized tires and your speedo is spot on, then it was calibrated wrong a while ago and you got lucky, or a previous owner who had the same size of tires on at some point had it calibrated for that size.
The trucks can't adjust for tire size. How is it supposed to "detect" the size of the tire? My SC 3815 said the truck was calibrated for 245/75R16 tires even though it came with 265/75R16 tires from the factory. If you have larger, oversized tires and your speedo is spot on, then it was calibrated wrong a while ago and you got lucky, or a previous owner who had the same size of tires on at some point had it calibrated for that size.
#10
On a truck with ABS it would be easy for the PCM to recalibrate itself. It is measuring wheel rotation and speed all the time and it can compare distance traveled to see if there's any change and readjust. Like I said, I don't know if it can do this, but there are a number of sites where people have said it can. I know the history of my truck since it was new and the original owner says he never had it recalibrated.