wow! highway mileage rules!

[ATiredExplorer]

I'm at 200 miles so far for this tank and and a little over or exactly at half a tank. I've never expierenced everday highway driving before I started college.

I wonder how bigger tires will affect this? I hear highway mileage improves?

 

[FROADER]

Bigger tires will effect it negatively. The reason it shows more mileage is because the speedometer is incorrect. It shows more miles than actually traveled, as well as less mph than you're actually going.

 

[ATiredExplorer]

Dang. I guess I'll just have to keep a close eye on my rpm's!

 

[aldive]

I wonder how bigger tires will affect this? I hear highway mileage improves?

They will generally reduce mileage.

 

[ATiredExplorer]

Yeah this mileage is too good to pass up. I'm thinking just 31's and new wheels.

 

[SkanlaxJMO]

it can actually go the other way too..it depends on gears...but yes generally mileage will go down.

 

[hunterdan]

Wouldnt the odometer show less miles than actually traveled? I went from 235's to 31s and I believe my highway mileage actually went up a bit. I was getting about 25 mpg highway last summer. I was doing a lot of driving between philly and harrisburg, about 120-140 miles depending on where I went. A lot of it depends on your gearing. I think the 3.73s are just right for my 31's on the highway and were a bit too tall for the 235s.

 

[FROADER]

You're right, it would show less. It would still be wrong so the mileage isn't actually better.

 

[aldive]

You're right, it would show less. It would still be wrong so the mileage isn't actually better.

You can use a GPS to calculate distance traveled to use in calculating gas mileage.

 

[Hokie]

With taller tires, your actual distance travelled will be less than indicated on the odometer. So your fuel mileage will seem worse. To get an actual representation of the MPG you have to correct the distance traveled. As the circumference difference between the tires, the change in distance traveled is a linear relationship. (C=2*pi*R, only R changes)

ie: 31"/29" (235 tire) = 1.068 or 6.8% percent more distance traveled per revolution.

So, if with taller tires your truck reads 17mpg, you actually got 17*1.068 = 18.17 MPG

I went from 235's to 32's and my speedo is off by 9.5% I checked this using the odometer and the mileage markers on the interstate. When I drove 40 miles on the interstate my truck would only register me traveling ~ 36 miles.

Keep in mind that your speedo will be off by the same percentage. My truck is now traveling ~ 66 mph when the speedo reads 60 mph.