A car's gear ratio is what determines whether it's best equipped for high acceleration and low maximum speed or the converse. Obviously, everyday driving is going to have situations that require both of these, which is why transmissions exist -- to change between the two as needed. Gear ratio is what determines whether a gear is better for high acceleration or a high top speed. It is the relationship between the pinion gear (the gear on your engine) and the ring gear (the gear on your transmission that connects directly to the wheels).
Open the Tahoe's hood and transmission casing and and find the pinion gear, which is the gear attached directly to the crankshaft. It is connected to the crankshaft through the clutch. The crankshaft is connected to the engine itself, as it is what moves when the pistons fire. So follow the piston to the crankshaft to the clutch and to the pinion gear.
Count the number of teeth on the pinion gear.
Find the transmission, which should be either attached to or very close to the pinion gear. This is because the pinion gear needs to attach to the transmission gear to function, so they can't be far apart.
Find the ring gear you want the ratio for on the transmission. There should be five or six, with four (or five) forward gears and one reverse gear.
Count the number of teeth on the ring gear you choose.
Divide the number of teeth on the ring gear by the number on the pinion gear. The lower this number, the lower the gear ratio and the better the gear is for high top speeds, and vice versa. The lower gears are high ratio and the higher gears are low ratio.
