I've made an excel spreadsheet to compare the tire sizes and actual mileage comparisons... There is some other junk in there, like fuel savings calculator, which likely will not be too accurate because if you are changing from a smaller tire to a much larger tire, the impact of the tire weight and likely undergearing will decrease you measured MPG. But, it will probalby work OK if you are looking at changes of an inch or less.

You can change things in yellow - and the rest of the numbers will update.

The number in green is what you would multiply your mileage by to get actual mileage when computing at the pump.

I hope this is useful to someone... there seems to have been a lot of questions about this stuff recently, and I figured I would adapt a sheet I already had put together for the forum.

Since I can't attach a file, I posted it here... http://spreadsheets.google.com/ccc?k...TwEg&hl=en

I think you need to have a google account to login and see it... but it's free. If there is a better way to post a file here, let me know.


Cheers,
Cartman

 

1BigRamaniac: I'm sure you are correct. I was just using the sidewall information. I think tire rack lists actual diameters for various tires.

 

I used this website to do some calculations. http://www.discounttire.com/dtcs/infoTireMath.dos[/align][/align]I read somewhere that The cats were recalled on 96 rams. I wonder if that might be part of the problem. I do a search and figure out how to check the plenum but is there a way to check the o2 sensor?[/align]