See full version: Gear ratio: How it affects horsepower, torque, and rear axle in trucks
Using a gear ratio calculator helps in finding an effective gear ratio for your vehicle with new tire size. It aids in determining the best ring and pinion gear ratio for your car; thus, optimizing fuel economy, performance, and everyday driving. [links]
Typically, gear ratios intend to balance performance, fuel economy, and the vehicle’s capability. Automakers select a final drive ratio that lowers the engine’s rpm; thus, efficiently meeting the government’s mileage standards. Optional axle ratios give more towing ability by increasing the engine’s available torque delivered to the axles.
What is the best gear ratio for towing?
If you do not want to disassemble your differential, you can find your axle ratio in the owner’s manual or repair manual. You can also locate your vehicle’s axle ratio by reading it off a sticker near the door latch on the front door on the driver’s side. Sometimes, it’s written as a code, but such codes should be in your owner’s manual. more
How do I determine my axle ratio? more
The primary function of gears is transmitting power from one part of a vehicle to another. In vehicles, gears transfer power from the crankshaft (a rotating axle that obtains energy from the engine) to the driveshaft, which ultimately sends the power to the vehicle’s wheels.
With our RPM calculator, you can calculate your engine's RPM based off of your vehicle's speed, tire diameter, rear gear ratio, and transmission gear ratio. Keep in mind that our calculator does NOT take into account drive train loss, road and weather conditions, or the skill of the driver. [links]
Mon-Fri: 8am-6pm & Sat: 9am-3pm CST
Engine RPM, or revolutions per minute, is defined as the number of times the crankshaft of your engine rotates within the span of one minute. Your vehicle's RPM can be calculated at any speed as long as you give the tire size, axle ratio, and final transmission gear ratio. Using this calculation, you can match oversized tires with new ring and pinion gears to get the engine RPM at highway speed you desire.
This can briefly impact on momentum, Jenner says, and instead advises smoothing this out by shifting on the cassette first – in effect getting the adjustment done early – then quicker moving across the chainrings to achieve an easier transition.
If your gears are too low (or, in other words, too easy), you might be left behind as you spin out. If they’re too high, the danger is you’ll be unable to turn the pedals fast enough when the going gets tough, or will come to a grinding halt on a steep climb.
It’s also possible to find other options, such the 46-36t chainset often found on cyclo-cross bikes, while some chainset manufacturers are now offering even smaller chainrings (for example, 48-32t), sometimes found on gravel bikes, where the smaller gears are appreciated for steep, off-road climbs. here
We’ll cover the impact your gear ratios have on power input, the importance of cadence, your options when it comes to gear ratios, and how to use your gears efficiently.
“If you’re over-geared and fighting to stay on top of the gear at an efficient cadence, every 10 or 12 seconds you’ll probably need to get out of the saddle to maintain the speed you’re travelling at, spending extra energy and effort,” Jenner says. more
Indeed, the terrain you ride is intrinsically linked to the gear setup you’ll need. Are you planning on riding lots of hills because you live in an especially lumpy area, or will you tend to stick to the flatlands?
EXAMPLE With Overdrive (30%): 1800 RPM / 656.93811 = 2.73:1 x 130 = 3.54:1
EXAMPLE With Overdrive (30%): 2000 RPM / 656.93811 = 3.04:1 x 130 = 3.95:1
A number of factors must be considered when selecting a rear-end gear ratio (ring & pinion set). Tire diameter, transmission choice (with or without overdrive) and desired highway cruising speed.
CONVERTING TIRE CIRCUMFERENCE TO REVOLUTIONS PER MILE
FORMULA: Tire Circumference in Inches / 12 = Tire Circumference in Feet
FORMULA: Number of Feet in a Mile / Tire Circumference in Feet = Tire Revolutions Per Mile
EXAMPLE (285x70R15): 96.446813 / 12 = 8.0372344
EXAMPLE (285x70R15): 5280 Feet / 8.0372344 = 656.94239 here
Tire diameter is the first consideration because styling and available space within the wheel opening dictate the size of tire / wheel combination that will be chosen for the car. The choice of a direct-drive (1to1) or overdrive (usually 30%) transmission will determine driveshaft RPM at cruising speed. A highway cruising speed of 60-65 MPH is considered a good target speed.
FIGURING TIRE CIRCUMFERENCE
FORMULA: Pi (3.14159) x Tire Diameter = Circumference in Inches
EXAMPLE (285x70R15): 3.14159 x 30.70 = 96.446813 more
The proper rear-end gear ratio can be selected using the following simple formulas whether using a direct-drive (1to1) or overdrive (usually 30%) transmission.