Did my MPG go down?

[The purple one]

I put on some 235 tires on my 93 and now I think the speedo is about 2 mph off. Is there a way to find out how many mpg I am getting without new speedo gears? Thanks

 

[triumphrider-1]

Whats the stock tire size?

 

[MountainMike]

And what is the aspect ratio/rim size of the 235's?

 

[The purple one]

I do not know the stock size. I will lookit up on Mon. when i get it back.

 

[94 lngbd]

a 93 2wd should be 225/70r-14

 

[MrE_Powers]

gps will help get you accurate mpg

 

[LearjetMinako]

There is a 9~10% difference in tire size. So when you do MPG calc, add 9~10% of the figure number to the total. Ex. If you got MPG= 200, 200 x 1.10 = 220 MPG. This should also correct the Speedo as well. Instead of 65mph, 65mph (indicated) x 1.10 = 71.5 (corrected indicated). A GPS should confrim the results.