315's

[rono]

After having the 315-75-16's installed, my first tank of fuel shows a loss of milage of about 4 mpg. At least that is what the computer shows. I know the milage is now off because of the tires but I don't know if it is that much. I can tell a change of power taking off because of the overall drive gear ratio. Does anyone know how to figure how much my speedometer is off going from 265's to 315's?

Thanks in advance, Ron.

 

[Rob Thomas]

Mine was off 7 mph,I have a relitive that works for DC he brought a computer home from work to adj. the speedo difference on my truck. It's right on now,I think the dealer can adj. yours.

 

[thepitts]

Try this site

See if this helps you http://www.volkswagen.org/tiresize.htm

 

[DEZLPWR]

Get an Abbott ERA Box....

I have one & my speedo is dead on with my 35" BFG's...

 

[Chipstien]

I did the same thing.....

and I am aproximatly 10% off. Just take your total mileage and multiply it by 1. 10 and you should get the real mileage. Good luck!

 

[Extreme1]

By the numbers, the 315's are 34. 6" dia which is 108. 71" in circunference. The 265's are 31. 65" in dia which is 99. 43" in circumference.



This yields a ratio of 1. 093295186. Oo. which is 9. 3%



Chipstien is good at 10%, the actual circumference will vary from the calculated value.



Oh, and yes, you will loose some milage and performance with the big tires. When I buy my next set (this fall) I will be going back to 215's, I lost about 1 1/2 mpg.

 

[rono]

Thinks for the replies, that is going to help a lot. I may go back to the 265's after these.

Ron

 

[KPhillips]

Try this web site for your calculator needs

If you need some fairly good calculators, go to this web site Gearing, and Wheel Calculators and look in the maroon header across the top of the screen. There are some pretty helpful calculators there that can come in pretty handy when your devciding on gears, tires sizes etc.



kerryp

 

[Vaughn MacKenzie]

Why go overkill or just stock? Go with something inbetween like 285s or 295s.

 

[RKohn]

Just because 315's look so good!!!

Oo. Oo. Oo.

 

[jsimpson]

My tire guy recommended 235's; I got 235's. I'm quite happy with them. I bought my truck for work. I drive my old Vette for looks!