im sure this can go in an another thread... call me retarded, but i cant find any info here that would tell me an equation that would tell me what my oversized tires are really doing to my odometer. i know that whatever its reading now is false since i have put on the bigger tires. but by how much more, i have no clue.

anyone know any sites or anything to figure stock vs. new tire sizes actual odometer readings?


FYI my original tire size was 235/75/r15 i upgraded to 31 10.50's on 15" rims

 

You went from 28.9" to 31", assuming your new tires are true 31's, many tires exaggerate. If they are actually 31's and you old tires are 29's, you speedo reads about 6.5% low. 65mph indicated is about 69 mph.

Frank

 

http://www.net-comber.com/tirecalc.html

http://www.ringpinion.com/Calculators.aspx

 

https://www.yotatech.com/forums/f123...eading-135596/

 

http://www.discounttire.com/dtcs/infoTireMath.dos

 

stop watch or a GPS works too....

 

I'd say the easiest, most accurate way would be with a GPS.

Another accurate way is to find the circumference of the wheel you took off and the circumference of the wheel you put on and divide the bigger number by the smaller number and get the percentage...

As mentioned, just because they say it's a 31" tire doesn't necessarily mean it is.

 

check your spare, if its original equipment and is 10.5 x 31 x 15, you are good to go. people get cheap when it comes to replacing worn tires and not all tire shops know/take the time to check what tires the vehicle came with from the factory.

my spare is 10.5 x 31 x 15 but the truck came with 225 x 75 x 15 when i bought it. vin plate shows 225 as the required size from the factory but thats not what it was originally equipped with.

lee