i just want to make sure i have the correct info about that subject. i want to get 4.56 gears and i hear the top speed of the truck will be affected. what will be the top speed? thank you in advance

For practical purposes, the top speed will be whatever your speed limiter is set at.

This whole concern over "top speed" is a made up issue. How fast are you planning on going?

I have 37" tires and 4:56 gears, and I can still easily hit 100.

shouldnt have a problem.....

now is that 100km's or 100mph??

Real simple math guys:

Find your overall gear ratio:
REAR GEAR x TRANS GEAR = OGR (over all gear ratio)

Find your RPMS @ any speed:
SPEED x OGR x 336 / TIRE HEIGHT = RPM


In overdrive I have been over 5400RPMs with 4.56 gears and 31.5" tall tires... How fast was I going?

SPEED SAFE, AIR RAM

wtf?! you can do over 150 with a ram? no speed limiter?

or is it at 155 mph? (your numbers ~156mph)

My bad... I have a 2002 with the .75 overdrive... That's important for the math to work. My overall gear ratio (OGR) is 3.42. Of course you could figure in some transmission slippage... but the math will surly get us into the top speed ball park.

SPEED SAFE, AIR RAM

ok guys i still dont get it. well after my superchip now i am not limited to any speed. i reach about 125 mph and i have 3.55 gears stock. will i get the same speed or less? i heard i can only reach 100 mph. i have 33'' tires.

what rpm are you topping out at?

I've hit well over 100mph with my gears...