Determining the perfect gear ratio for your truck is as complex as picking the perfect tire. If you have a small engine that can withstand freeway rpm, we often recommend a lower (numerically higher) gear ratio such as 5.29s with a four-cylinder. If you are running a tire larger than stock, you will also want a lower (numerically higher) gear ratio, partly due to the additional torque needed to get a larger, heavier tire moving. If your engine has a lot of low-end torque but doesn’t like to rev at high rpm, then you should usually opt for higher (numerically lower) gear ratios such as 4.10s with a big-block. Of course, mixing in overdrive transmissions will allow you to run lower axle gear ratios when running down the highway.