Many of our customers say that when they drive their car on the highway, their engine is doing 3,000 RPM or more just to go 60 miles per hour. They do not want to cruise at that high an RPM and they wonder how much an overdrive transmission will reduce their RPM at that speed. SST’s Speed Analyzer can help you determine the speed you’ll travel at your ideal RPM with the different transmissions we offer. 

It’s easy to use the Speed Analyzer. Start by selecting a transmission. If you want to check a transmission not listed, no problem, just plug in the gear ratios for each gear. Next add the RPM, the rear axle ratio (determine your rear axle ratio), and your tire height. If you don’t know the tire height, you can put the tire size in the calculator below the Speed Analyzer to figure it out. Once the Speed Analyzer is filled out, click “Calculate Speed” and note the MPH of each gear at that RPM. If you check a second transmission, you’ll need to check all the boxes to make sure they still have the right information for RPM, tire size and gear ratio and correct it if it changed before clicking “Calculate Speed” again.

You can use this calculator to plan ahead too. For instance, if you know you plan on changing out the wheels and going to a larger tire size, you can compare the speeds for different tire heights. You can do the same with different rear axle ratios if you plan on changing out the differential gears or the rear axle.

You can also use the calculator to determine what it’ll be like in stop and go traffic or what your top speed might be by changing the RPM and clicking “Calculate Speed”. The first few gears may be more of a determining factor than the overdrive gear in some cases because some tire/rear axle/transmission combos may put the RPM sweet spot of your engine in an awkward place where you’ll be shifting up and down constantly through town or the first gear may be geared too low for your set up and cause the engine to stall more easily at launch.

As always, our technical sales department can talk you through the options to help you make the best choice for your driving style and preferences.