How To: Calculate mpg/miles travelled with bigger than stock tires

[HazardousEdge]

okay so i saw this on another forum and i thought id explain it myself...the concept is relatively simple..this is only for people who have no recalibrated their speedometer/odometer


Current size/stock size (must be in inches obviously) (in my case 31/28.9)=1.073

actual miles= Reported miles on odomter X (current/stock) (ex: 300x1.073=321.9)

321.9= actual miles travelled

Mpg= actual miles / amount of gas you put in
(321.9/19)=16.9 miles per gallon


btw i really did search for this lol

ofc you have to account for ur tires wearing down if you want an EXACT measurement and offroading miles dont count cuz of wheel spin

 

[Mac]

One thing I have done on a couple of 200 mile interstate runs is just to check how accurate the odometer is using the mile markers. Mustang is about .5% accurate and the Rangers are all right around 1-1.5%. Got to have a good accurate start to the calculations other wise that math is just paper work. I'm kind of sad so many people have no crasp of math like that today.
Dave of the Nord

 

[HazardousEdge]

yeah...fml because i never checked the accuracy with the stock tires even tho i had the means of checking lol oh well and we dont have that many mile markers in california unless youre on a loop of some sort

 

[jhammel85]

Awesome. Thanks for posting this! I want to give this a shot at my next fill up.

 

[jhammel85]

By the way, I used part of that formula to find out how many extra miles my truck has actually gone since I added bigger tires. The owner before me had somewhat bigger tires than stock under it too. so I've been curious to see what the actual milage is.

Here is an example for anyone who's curious (using the TS's numbers):

Take your stock tire in inches and new tires in inches -- (31/28.9)=1.073.
Multiply your odometer (or like this, a guess as to how long it's had these tires) -- 50,000

50,000*1.073 = 53,650.

It's not perfect but it might help if you were wondering about it like I have been. My truck went from 195's to 215's for about 44K before I added my 30's on it, according to receipts from the previous owner.

 

[HazardousEdge]

yeah i have the miles written down for when i added the 31's, im hoping when i have it recalibrated they can just put that number in there.....can they?

 

[HazardousEdge]

anyone else ? lol