2.64 gear ratio?

I had a 430/470 Detroit, 10 speed direct and 2.79 axle. It was OK but Given the choice, I would have picked 2.64. I had a pre EGR engine. My longterm average mpg was 7.3. It never dropped below 7.1. I reset the mpg every year at the annual inspection

 

To 370exhd: a 3:36 ratio is "taller" than a 3:90. Lower number= higher ratio. I would have to agree with you about the direct versus the overdrive transmission. I have driven many different transmission / axle ratio combinations. I got the best fuel mileage with an RTX 10 speed and 3:91 axle. The RTX overdrive ratio is more compatible than the older RTO ratio which was about 75% if my memory is correct. During the era when a 4:11 ratio with 10 speed direct was very common, I used to change a 10 speed direct transmission to an RTO by swapping the first and third gears on the main shaft and the counter shafts. The trucks top speed would be too high with 11:24.5 tires

 

Where do I find out what Gear Ratio my Carrier x4 reefer has?

 

I'm looking at this same setup right now. How much over 80 000 k were you? Did you have any startability problems with the weight? I run around 80-100 occasionally 110 just like to get some real world reviews hauling heavy with a dt12 and 264 gears

 

I have a 2020 cascadia with dd15 and dt12. With 2.47 gears. Truck came with 24.5 tires but were changed to 22.5 low pro. Before I bought a truck. At 70mph I'm running at 1500rpm. Its driving me crazy. Can that be changed. Thank you.

 

I have a 2020 cascadia with dd15 and dt12. With 2.47 gears. Truck came with 24.5 tires but were changed to 22.5 low pro. Before I bought a truck. At 70mph I'm running at 1500rpm. Its driving me crazy. Can that be changed. Thank you.

 

Put the bigger tires back on. RPM will drop. But as always every action has a reaction. Taller tires also equals more rotating mass.

 

Is there a way to change program to drop my rpm. Maybe calibration or something. for 22.5 tires. I really don't want to run 24.5. Trailer is 22.5.

 

The engine is connected directly to the wheels when going down the road so the only ways to lower the RPM are to either slow down, change axle/transmission gearing or change tire size.