cat c-15 18 speed 3.08 ratio???

He won't gain anything going to 11r tires and running faster.

 

It also depends on the truck, driving style etc. I picked up .5 when I put mine on, but I's also running a 3406E CAT, that would make more difference than say, if you were running a 11.1L Detroit.

 

I agree with yea there.

 

I was driving an 07 w900l with 3.55s and 18 speed. I was running 80ish at 1500. We put Pittsburgh power mufflers on it and it ran 11R24.5s and got 6.0-6.5 we were gonna swap it over to a 6nz but we never got the chance

 

Got 6nz with pdi tune a 18spd with 3.08 rears 11x22.5s rubber. My choice would be 3.25 rears better compromise. I Got a heck of a deal on some weller remans that's why the 3.08s wish I would have just stuck with my original thought and got the 3.25s.

 

I know of a 475 Acert that had 3.36s, and one driver drove it during the day, and another at night. The driver during the day was a stickler for speed limits and fuel mileage, and was getting I think about 2 miles more to a gallon than the night driver. Same truck and loads. The owner knew, but did not care, as he had a lead foot as well....

I drove the truck once, and it was a dog. But then, I remember the 475s back in the late 90s and early 2000, with 3.90s and 24.5s....race cars.