mpg

[Ben470]

I would like to know what are the most popular rear gear ratios used in straight trucks (D units). I'm looking to buy a truck and would like to know what will give me good fuel economy without sacrificing too much power. I know engines and trannys have alot to do with it all too but I can get a basic idea of fuel economy by looking at rear gear ratios and final drive ratios.

 

[Broompilot]

The Dealer can probably to a better job of specs than we can. Trans/Engine HP will make a big difference, so there is not just one answer.

Someone may have a set up that he/she just loves ISC 285 HP Allison Auto, 390 close to rear. Works just fine for me but I am a bit jelous of those with 10spds getting 1 1.5 better fuel economy than I. There gear ratio would be different than an Allison Auto.

Dealers do an excellent job at this. Example If I was set on MPG and went down to a 350 rear I would suffer in Power, she pulls great and still gets respectable MPG.

 

[guest]

Well, on my truck back in 1995 it was an Fl60 with 373 rear end and that truck got great mpg almost 14 mpg. Dan Schultz sold me this truck when he worked for Freightliner of Knoxville. My truck now has the Same rear end with a 3126 Cat and it get around 11 mpg when I don't drive over 65 mph. I hope this helps