The best ratio is to have your engine run at the sweet spot RPM at the speed you will be running most of the time. If you run the east coast mainly then 65 if you run out west allot the 70 or 75 in the sweet spot. Usually the Detroit’s like it around 1400-1550 or so is a good range.

In its most simplistic form, the truck’s axle ratio is the number of revolutions it will take the driveshaft to spin the wheel once. Different axle ratios change the number of teeth in the pinion, which is connected to the driveshaft, and the ring gear attached to the wheel end drive through the axle differential.

A 3.73 ratio is suitable for regular light towing. If you plan on towing a fifth-wheel trailer or anything heavier than 5,000 pounds, you should consider a 4.1 axle ratio. A 4.1 ratio allows a towing vehicle to start moving without as much throttle.

3.25s are a good all around gear.

No. That is the prime reason that horsepower is used to compare engines. Torque is completely affected by gearing, so torque is hard to compare across vehicles.

For instance, a 3:31 gets better fuel economy than a 3:73. On the other hand, a 3:73 or perhaps a 4:10 will tow much more, while fuel economy greatly drops. The most popular rear end ratio in trucks today is the 3:55, which sort of averages towing power and fuel economy.

Rear end gears (2.79’s, 3.00’s, 3.25’s, etc) are great for freeway driving, bit not good for 0-60 MPH or accelerating from a dead stop. Shorter gears (higher numbers) are much better suited for accelerating, such as 3.55, 3.73, 3.91’s, 4.11’s etc. Always remember, for very “give” there is a “take”.

Use the 2.64 to drive faster, above 60 mph and the 2.93 below 60 mph. These ratios are capable of great fuel mileage. The 2.64 is comprable to a 3:55 with a double overdrive. This is a Direct Drive Transmission, a 1:1 ratio.

3.55 will give you a little better gas mileage on the highway and slightly more highway oriented performance. 3.73 may be better for towing, lower end power (off the line acceleration), and may result in worse gas mileage on the highway.

4.10:1

A numerically higher axle ratio provides a mechanical advantage to send more of the engine’s available torque to the rear tires (and front tires, in a four-wheel drive vehicle), but you pay the price at the fuel pump. So, a truck with optional 3.73 gears will tow a heavier trailer than one with 3.55 or 3.21.

The conventional procedure for selecting gear ratios is to pick ratios that run the engine rpm to redline at the end of the medium and longest straights, and pick the lower gear ratios to minimize the rev drop at each shift. This method minimizes the number of shifts per lap.

How to Find Out the Gear Ratio With the VIN Number

1. Find the VIN of your vehicle.
2. Identify the VDS section, the fourth through eighth digits of the VIN.
3. Find a guide online, such as Edmunds.com or Decode This, or contact an automobile dealer to help interpret the VDS.

Vehicle Description Section The fourth through eighth digits describe your vehicle’s model, body type, restraint system, transmission type, and engine code. The ninth digit is the check digit, which is used to detect fraudulent VINs.