4.0 fuel mileage readings

[1986fordranger]

hi . i recently bought a 1999 ford ranger XLT 4x4 automatic extra cab with the bigger 4.0l v6 . also is pretty low mileage at alittle over 92,854 as of current . also has abit under sized tires (225/75r16) . the truck should have 245/75r16's . now this is my question driveing in country/city driveing im getting roughly 20 mpg (miles per gallon of gas) . seems pretty decent in my opinion . the question is are the smaller tires messing with my gas mileage readings ? . in theory i was thinking the smaller tires mean it takes more revolutions of the tires to go the same distance as the stock sized tires . whitch would mean im going more miles down the road then the trip odometer reads . true or false ? . any opinions on this topic would be great . thanks

 

[hondaxr650]

Yep. Your speedometer is gonna read high and you'll rack up some extra miles on the odometer. Not sure exactly how much, you'd have to do the math. tirerack.com is a good place to look up tire specs. Most of the tires have the revs per mile listed in the spec section.

 

[notaprob]

By using the the (225/75r16) instead of the factory (245/75r16) , you are gaining 4% more mileage on your odometer than you actually are traveling. So if you are getting 20mpg, take away the added 4% and you are actually getting 19.2mpg. That is pretty much what I get with my stock tires.

 

[1986fordranger]

thanks for the info guys . happy holidays