i am putting a 6 in and 315 75 16 bfg mt on my 05 lly. anyone out there running that tire? Did you lose much power?

I lost quite a bit of power with a 315/70/17 (just a bit smaller). The 40hp Predator tune brought it back and then some.

you are going to lose a little bit of power, you speedo is going to be off like crazy, but you can more than make up for the power loss with any 40-60 hp chip and then some.

Of course you can always re-gear to 4.10 or 4.56 but its a lot easier to add a tuner like the predator.

Run that same setup all the time, some power loss, some mileage loss, great look though!! Put a tuner in and off you go!! You'll have to drive alot to break even on cost of extra fuel and cost of regear. Trust me, I figured it out, at at 40K KM's a year, it was supposed to take me nearly 7 years to break even. Just a thought.

Also to save you some time with calculations, your speedo will be out approx 12% - 13%. Fuel mileage is out about 30% from stock.

Here are 315 75r 16's on American Racing D-8s

http://www.dieselplace.com/forum/attachment.php?attachmentid=5286&d=1118499378

I noticed little to no mileage drop. 5% tops

Bitterman, that truck of yours is huge. How do those dual 315's fit on the back? I just put a set of 235's on the back of my old dually and the clearance between the tires was close. Man how did you make them fit?

Bitterman, that truck of yours is huge. How do those dual 315's fit on the back? I just put a set of 235's on the back of my old dually and the clearance between the tires was close. Man how did you make them fit?

I had some custom billet spacers made to accomodate the tire width. Here's a pic of it from the back.


I have about 2 inches of clearance between them and they fit well. http://www.dieselplace.com/forum/attachment.php?attachmentid=5287&d=1118499378