How many MPG's off is my car because of slightly larger tires??

[panamacolin]

Hey guys!

Just wondering how many mpg's my cars tripometer will be off because the VX stock tires are 165/70-13 and I am running 175/70-13...

Thanks in advance, everyone on here has been great!

[mrmad]

Here is a circumference calculator on discounttire.com. You might want to try to verify how accurate your odometer is overall. My CRX has 185/60/14s on it which should be about 4% larger in circimference then the stock 13 tires. I used Google Earth to measure about a 30 mile section on my commute to try to see if I was really getting 4% lower mpg then I was calculating, and it turned out the odometer was pretty much dead on with the 14" tires. I guess the stock odeometer is about 4% high.

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

[panamacolin]

2.54%...is what it says...mind running running it for me to see if I did that correctly...

Thanks!
Colin

[mrmad]

Tire calculator says 165/70/13 has a circumference of 69.41 and 175/70/13 is 71.14. This is 1.73" more. 1.73/69.41 is 0.0249 or 2.49% more. The Sunday night football game must be pretty boring to make me want to calculate tire circumferences.

[cfg83]

panamacolin -

I used a GPS to calibrate/correct my odometer :

New shoes (aka tires)
http://www.gassavers.org/showthread.php?t=3699

CarloSW2

[panamacolin]

cool, ill have to try the gps thing