I bought a used Automatic 2010 Gt back in January, the sticker on the window said it had a 3:31 Axel however I find the gears are a little higher than I'd expect for that. They RPMs at 120kph or around 70 to 75mph it sits at about 2250 and at 130 to 140kph or 80 to 85mph its pretty much at 2400-2500rpms. I kind of figured that would have been more what a 3:55 would be at. I hear some people saying that with 3:73 they are around 2800 to 2900 rpm at 80 so maybe that's right. Just wondering if that's correct for a 3:31? Obviously the rpm is fine since the norm for most 3v have slightly higher rpms on the highways and I find my gas mileage really good too as long as I keep her no more than 2600rmp but at that point I'm risking a hefty ticket lol.

What rpms are you guys at around those speed and with what ratio? Is mine correct for 3:31 or might I have a different set up from what the dealer thought it had?

Thanks!

 

there are some on-line calculators where you can figure this out . . . it depends on the transmission gearing, the tire size, and the rear end ratio; if you know two out of three, and you know the RPM at a given speed, you can figure out the rest

attached Excel worksheet has the math built in to it, and can be used to figure it out, if you don't find an online tool for it . . . pretty sure the links are in threads on here somewhere