you will learn alot.
you need to digest these in usable sections.
first, you need to learn the differences in the different ratios - IE 4.10 4.56 4.88 and 5.29 gears.
i do not know what your level of experience is with this, so ... when an axle has a 4.10 ratio in it, the drive shaft will turn 4.1 times every time the rear axle it self turns 1 time. (4.10:1) when you run a 5.29 ratio, the drive shaft will turn 5.29 times to every 1 revolution of the axle. (5.29 to 1)
that should help you visualize what the transmission/ engine is having to do. The higher the RPMS, the more fuel is consumed (on average - there are exceptions) - so the trick is to find a balance between power and mileage. (the higher the ratio, the more "power" (seat of the pants power) is available. This is because the engine is spinning faster, and closer to its "power band". (Example: when running stock 4.10 gears, the engine is turning at 1900 RPM at 55 mph. to accelerate to 65, it would increase to 2100 RPM. This engine (and most) make most power between 3000 and 4000 RPM. the increase is slower because of the power needed is lacking in that RPM range. take a 5.29 gear set: same 55 to 65 mph acceleration is ranging in between 2400 and 2900 RPM, much closer to the "power band" for this engine. it is easier to accelerate in that range than down low. the hand off is fuel mileage.
in addition to the power band is the mechanical advantage gained from the higher ratio. it is easier to turn the tires with 5.29 gears than with 4.10 gears.
HowStuffWorks "How Gear Ratios Work"
those two items comprise the primary reasons for the use of higher ratios when changing tire size. (the secondary reasons would be to correct the speedometer accuracy and personal preference) IMO.
hope this helps.
you need to digest these in usable sections.
first, you need to learn the differences in the different ratios - IE 4.10 4.56 4.88 and 5.29 gears.
i do not know what your level of experience is with this, so ... when an axle has a 4.10 ratio in it, the drive shaft will turn 4.1 times every time the rear axle it self turns 1 time. (4.10:1) when you run a 5.29 ratio, the drive shaft will turn 5.29 times to every 1 revolution of the axle. (5.29 to 1)
that should help you visualize what the transmission/ engine is having to do. The higher the RPMS, the more fuel is consumed (on average - there are exceptions) - so the trick is to find a balance between power and mileage. (the higher the ratio, the more "power" (seat of the pants power) is available. This is because the engine is spinning faster, and closer to its "power band". (Example: when running stock 4.10 gears, the engine is turning at 1900 RPM at 55 mph. to accelerate to 65, it would increase to 2100 RPM. This engine (and most) make most power between 3000 and 4000 RPM. the increase is slower because of the power needed is lacking in that RPM range. take a 5.29 gear set: same 55 to 65 mph acceleration is ranging in between 2400 and 2900 RPM, much closer to the "power band" for this engine. it is easier to accelerate in that range than down low. the hand off is fuel mileage.
in addition to the power band is the mechanical advantage gained from the higher ratio. it is easier to turn the tires with 5.29 gears than with 4.10 gears.
HowStuffWorks "How Gear Ratios Work"
those two items comprise the primary reasons for the use of higher ratios when changing tire size. (the secondary reasons would be to correct the speedometer accuracy and personal preference) IMO.
hope this helps.
