Gear Ratio Calculator For Bigger TiresIf you know specific information about your vehicle (gear ratios, RPM, etc. 30 is the best for fuel economy for 35'' tires. The chart is based on RPM levels at 65 mph (105 kph) and a drive train running at a 1:1 gearing ratio, meaning the transmission and transfer case are passing power straight through at a one to one ratio without reducing or overdriving the engines rotations per minute before it reaches the differential. 73 New Gear = (New Tire Size / Old Tire Size) * Current Gear Ratio 4. 4) + WHEEL DIAMETER = OVERALL TIRE DIAMETER For Example: 235/45ZR-17 (235 x 0. In effect your tire has two diameters. 73 gear ratio requires 3. Current Gear Ratio – 3. Next find the new tire size on the left of the chart and look across to find the RPM closest to your original, the ratio listed at the top of that column will be. - Click on the pull down under Top Gear and set how many gears your transmission has -Enter your individual gear ratios (you can google your trans to find gear ratios) (you can also click on compare ratios to see what a different trans would do) -Set your tire diameter. For the Tire field, enter your tire diameter in inches. Nov 19, 2022. Use our gear ratio calculator to find the effective gear ratio your vehicle will have with a new tire size. I want to get back my MPG any comments or suggestions?. Find What Gears To Run After you add taller tires to your truck or SUV, It’s fairly simple to figure out what gear ratio you’ll need or what rpm you’ll be cruising at with these two formulas:. Using the chart, first determine what your original gear ratio and tire size are, then follow the lines to find your approximate RPM at 65 MPH. The actual run out of the tire can be as much as 2 to 3 inches less than what the circumference of the tire measures. This gear calculator will get you back to a ratio that's closer to your original. To solve the above problem: Enter the diameter of the tire, D = 20 inches. 4) + WHEEL DIAMETER = OVERALL TIRE DIAMETER. 12 by your tire diameter. To use our calculator, simply enter your tire size, gear ratio, and engine speed in RPM into the fields provided and click “Calculate. Differential Gear Ratio Calculator Calculate your differential gear ratio from RPM, tire size and desired MPH Ring Gear/Pinion Gear Teeth to Gear Ratio Enter the # of Pinion Gear. Assume the number of teeth on driving gear as 40. So, the taller tire will effectively reduce the gear ratio from a 4. Ring and Pinion Setup Specs - Ring and pinion gear setup specifications for popular axles. Gear Ratio Calculator. And here's a formula that you can use to calculate your vehicle's rear axle gear ratio:. This calc can be used to find a new gear ratio. Using the chart, first determine what your original gear ratio and tire size are, then follow the lines to find your approximate RPM at 65 MPH. You can also check out our tire size calculator, wheel offset calculator, tire height calculator and tire comparison calculator. Current Gear Ratio – 3. The left side of the calculator requires all three entries. Transmission Ratio RPM Calculator Determine your engine’s RPM based on the transmission gear ratio, tire height, MPH, and the ratio of your ring gear and pinion gear. Ever wonder what your low-low-low gear ratio is, your. Here's a formula you can use to calculate your vehicle's tire diameter: (CROSS SECTION WIDTH x 0. Ian shows you how to find the effective gear ratio on your vehicle when you upgrade to bigger tires with this equation on a PowerNation Extra tech tip. 35" is the norm (one of the most common tire size upgrade) I dont know the limits of the suspension components but i know buying a properly engineered kit, alignment and balancing of your new tire/wheel, will keep the rest of your suspension components happy. This calc can be used to find a new gear ratio. Your axle gear ratio determines how many times your driveshaft needs to rotate in order to complete one full tire rotation (a 3. It also tells me the "new ratio needed" is 3. (Use Find new Gear Ratio with new tire size chart) second one down. The perfect gear ratio for 35-inch tires is 4:1. Bigger tires are more functional, look better, and rob you of power. This is especially helpful when trying. Ring-and-pinion selection made easy! Save yourself the headache and let us figure out your ring-and-pinion gear ratio! Just type in your info (example: 5000 RPM), press calculate, and you’ll get the right ratio without the guesswork. Bigger tires can help you crawl up those slick rocks, look cool, and rob you of power. Assume the number of teeth on driving gear as 40. Gear Ratio and Tire Size Chart. (Use Find new Gear Ratio with new tire size chart) second one down. Good "rule of thumb" calculation is to mutiply. To determine your tires true diameter in relation to determining what speedometer gears you need, measure from the ground up to the center of the axle then multiply by two. Next find the new tire size on the left of the chart and look across to find the RPM closest to your original, the ratio listed at the top of that column will be your first choice for ratio. For Example: 235/45ZR-1 (235 x 0. Just type in your tire size, aspect ratio, diameter, old gear ratio and it will calculate it for you. Calculate GEAR, RPM, MPH, TIRE DIAMETER: Wallace Racing BACK to Calculators Todays date is 5/12/2023: This calculator is for entertainment value only. Effective Gear Ratio : 1. New Gear Ratio = (RPM * New Tire Diameter)/(mph*336) So if you want to mount 34 inch tires,. Transmission gear ratio. Tire Size Converting from metric tire size to the more common inches used in those larger 4-wheeling tires can be handy. The chart is based on RPM levels at 65 mph (105 kph) and a drive train running at a 1:1 gearing ratio, meaning the transmission and transfer case are passing power straight through at a one to one ratio without. Speedometer ratio adjustment calculator. The following formula is used to calculate your new optimal gear ratio after installing bigger tires. This calculator will provide the speed of the vehicle based on transmission gear ratio, engine RPM, tire height, and the ring gear and pinion gear ratio. Gear Ratio Calculator. 73 gear ratio requires 3. GEAR RATIO GUIDE FOR LARGER TIRES. Using the chart, first determine what your original gear ratio and tire size are, then follow the lines to find your approximate RPM at 65 MPH. Calculate GEAR, RPM, MPH, TIRE DIAMETER. The perfect gear ratio for 35-inch tires is 4:1. It is advised to round to the next lower ratio to account for increased rolling resistance, and reduced aerodynamics from being lifted. This chart provides values that represent a 1:1 ratio on a manual transmission. Transmission gear ratio. New Gear Ratio = (RPM * New Tire Diameter)/ (mph*336) So if you want to mount 34 inch tires, now we can calculate the new gear ratio. Mine is in regards to that, I am trying to work out how I can add larger tires tires and maintain as close to possible the speedo/odo, and more importantly ECU programming - this can include switching gears out afterwards if necessary. One way to compensate for this is to swap out your differential gears. Use our simple Gear Ratio Calculator to quickly find the correct gear ratio for your ring and pinion gear set. The right side will show the results. For highway cruising and best fuel economy stay towards the. Off-road drivers and rock crawlers build their vehicles with low (numerically high) crawl ratios because not only does that increase torque. Ring and Pinion Setup Specs - Ring and pinion gear setup specifications for popular axles. Ever wonder what your low-low-low gear ratio is, your "crawl ratio"? You'll need to do a little research by finding. 4) + WHEEL DIAMETER = OVERALL TIRE DIAMETER For Example: 235/45ZR-1 (235 x 0. Use this calculator to determine your gear ratio and vehicle’s speed in any gear and any engine RPM for best performance. The calculation is your new tire diameter, divided by your old tire diameter, multiplied by your old axle ratio, will equal your new axle ratio: For towing or performance, you would want. 327" And here's a formula that you can use to calculate your vehicle's rear axle gear ratio:. Once all this information is known use the following formula to get the accurate differential gear ratio for the larger tires: Example: The rpm is 2806 at 105 km/h (65 mph), the current tires are 29 inch, the factory ratio is 3. 10 with 35'' tires or bigger tires? Does the swap is worth? on the gear ratio chart shows that 4. The colors represent ideal RPM's at highway speeds (65). Effective Gear Ratio : 1. These gear ratios are calculated by engineers to maximize torque, acceleration, engine RPM at highway speeds and ultimately gas mileage, all while taking into account the known tire diameter. Determine the size of drive gear for the speedometer given the tire size is 20 inches and the axle ratio is 3. 4) + WHEEL DIAMETER = OVERALL TIRE DIAMETER For Example: 235/45ZR-17 (235 x 0. Enter the values on the left and press Compute. New Gear = (New Tire Size / Old Tire Size) * Current Gear Ratio. Using the chart, first determine what your original gear ratio and tire size are, then follow the lines to find your approximate RPM at 65 MPH. One way to compensate for this is to swap out your differential. New Gear Ratio When you get larger tires you have to lower the gear ratio to preserve fuel consumption. The left side of the calculator requires all three entries. 4) + WHEEL DIAMETER = OVERALL TIRE. Ring-and-pinion selection made easy! Save yourself the headache and let us figure out your ring-and-pinion gear ratio! Just type in your info (example: 5000 RPM), press calculate, and you'll get the right ratio without the guesswork. Scroll through the list of popular transmissions to find yours. Use our gear ratio calculator to calculate your new gear ratio and rpm. One way to compensate for this is to swap out. 35" is the norm (one of the most common tire size upgrade) I dont know the limits of the suspension components but i know buying a properly engineered kit, alignment and balancing of your new tire/wheel, will keep the rest of your suspension components happy. gear ratio = (π × diameter of input gear)/ (π × diameter of output gear) Simplifying this equation, we can also obtain the gear ratio when just the gears' diameters or radii are considered: gear ratio = (diameter of input gear)/ (diameter of output gear) gear ratio = (radius of input gear)/ (radius of output gear). You can try various combinations to come up with an appropriate combination of ring and. You can also check out our tire size calculator, wheel offset calculator, tire height calculator and tire comparison calculator. Find What Gears To Run After you add taller tires to your truck or SUV, It’s fairly simple to figure out what gear ratio you’ll need or what rpm you’ll be cruising at with these two formulas:. To determine your tires true diameter in relation to determining what speedometer gears you need, measure from the ground up to the center of the axle then multiply by two. 12 by your tire diameter. This 4x4 Calculator can help you to find the gear ratio closest to the original setup. The Gear Ratio Calculator will determine the ratio of a gear set, based on the number of teeth on the ring gear and teeth on the pinion gear. The gear ratio for bigger tires is calculated by the equation: G = \frac {A \times R} {1001} where, A – Axle ratio (number of revolutions the transmission output shaft needs to make to spin the axle for one complete turn) R – Tire revolutions. ) then use the Gear Ratio calculator, it's probably a little more accurate. com/gear-ratio-calculator/), that will effectively change the gearing 3. 21 gears, it would be advised to purchase 4. 30 is the best for fuel economy for 35'' tires. 22", a 21" diameter is about 95% of the diameter of a 22", or a 22" is about 5% bigger, so changing tires from 21" to 22" is not as large of a ratio change as changing front sprocket one tooth (8% compared to 5%), thus you can go larger rear. Now tires you can calculate the same way, just use outside tire diameter to compare tires 21" vs. So, I know there are a TON of threads about gear ratios - specifically 3. Gear Ratio Calculator Use our simple Gear Ratio Calculator to quickly find the correct gear ratio for your ring and pinion gear set. Gear Ratio And Tire Size Calculator When you change your tire size you need to make sure you have the right gearing to get optimal fuel economy and power. These gear ratios are calculated by engineers to maximize torque, acceleration, engine RPM at highway speeds and ultimately gas mileage, all while taking into account the known tire diameter. 78:1 by our gear ratio to create our effective ratio: 4. The chart is based on RPM levels at 65 mph (105 kph) and a drive train running at a 1:1 gearing ratio, meaning the transmission and transfer case are passing power straight through at a one to one ratio without reducing or overdriving the engines rotations per minute before it reaches the differential. Calculate GEAR, RPM, MPH, TIRE DIAMETER. If you don't know, scroll to the bottom of the web page (under rpm/speed table in blue), there's a diameter calculator there, punch in your tire size, copy diameter and paste (you can also compare tire sizes here) Now choose km/h or mph and click on calculate. Effective Gear Ratio : 1. For the Tire Height field, enter. Transmission Ratio RPM Calculator Determine your engine’s RPM based on the transmission gear ratio, tire height, MPH, and the ratio of your ring gear and pinion gear. A basic method to calculate is to mutiply. 56) The below table can be used to get a rough idea on gear ratios. We can calculate the new ratio like this. Gear Ratio Calculator Wish List Savings Central Shop by Brand Shop Your Passion Shop Your Passion Truck / SUV Jeep® Gifts, Clothing, & More Restoration Stock Replacement Late Model Muscle Tools Circle Track Street Rod Powersports Paint & Body Marine Jr Dragster Shop Departments Air & Fuel Delivery Air & Fuel Delivery Loading. Use our simple Gear Ratio Calculator to quickly find the correct gear ratio for your ring and pinion gear set. The following chart of Tire sizes and axle gear ratios are meant to give a general idea of the relationship between the differential gear ratio and the tire size and what effect the ratio has on power output and fuel economy. This calculator will provide the speed of the vehicle based on transmission gear ratio, engine RPM, tire height, and the ring gear and pinion gear ratio in the rear end axle differential housing. The calculation is your new tire diameter, divided by your old tire diameter, multiplied by your old axle ratio, will equal your new axle ratio: For towing or performance, you would want. gear ratio = (π × diameter of input gear)/ (π × diameter of output gear) Simplifying this equation, we can also obtain the gear ratio when just the gears' diameters or radii are considered: gear ratio =. Enter the values on the left and press Compute, the gear calculator will take care of the rest. The formula for gear ratio is T2/T1 or T2 divided by T1. Now tires you can calculate the same way, just use outside tire diameter to compare tires 21" vs. Here's a formula you can use to calculate your vehicle's tire diameter: (CROSS SECTION WIDTH x 0. These calculations are assuming a manual transmission with a 1:1 ratio. Calculate GEAR, RPM, MPH, TIRE DIAMETER. OEM Tire Diameter: OEM Gear Ratio: New Tire Diameter: Recommended New Gear Ratio: (Round your result up or down to the nearest standard gear ratio below. The gear ratio for bigger tires is calculated by the equation: G = \frac {A \times R} {1001} where, A – Axle ratio (number of revolutions the transmission output shaft needs to make to spin the axle for one complete turn) R – Tire revolutions. Your have increased the size of your tire, what gears should you buy? Old Tire Size – 31” New Tire Size – 35” Current Gear Ratio – 3. Gear Ratio and Tire Size Calculator - 4x4 and Jeep Ring & Pinion When you change your tire size you need to make sure you have the right gearing to get optimal fuel economy. This calculator will get you back to a ratio that's closer to your original. Ring and Pinion Gear Ratio Calculator Enter your original tire size and gear ratio into the form below along with your new tire size to find your recommended ring and pinion gear ratio. Current Gear Ratio – 3. For the Tire field, enter your tire diameter in inches. This gear ratio and tire diameter chart is meant to give you an approximation of ideal RPMs at highway speed (65 mph) for three situations: fuel economy, every day driving and increased towing power. Old Tire Diameter: New Tire Diameter: Current Gear Ratio: New Gear Ratio:. Speedometer: Actual: Formula used (New Tire Diameter / Old Tire Diameter) * Speedometer MPH = Actual MPH. For a tire size to be considered within a specific RCI, the calculated RCI of the tire must be between -0. com - Bigger Tires Going to big tires is great but depending on how much taller you go over stock, you are adding stress on your transmission which can be relieved by adding the appropriate gears. Gear Ratio Calculator Wish List Savings Central Shop by Brand Shop Your Passion Shop Your Passion Truck / SUV Jeep® Gifts, Clothing, & More Restoration Stock Replacement Late Model Muscle Tools Circle Track Street Rod Powersports Paint & Body Marine Jr Dragster Shop Departments Air & Fuel Delivery Air & Fuel Delivery Loading. 327" And here's a formula that you can use to calculate your vehicle's rear axle gear ratio:. The calculator will now return the number of revolutions per mile, R = 1008. Gear Ratio & Tire Size Chart. This calculator will provide the speed of the vehicle based on transmission gear ratio, engine RPM, tire height, and the ring gear and pinion gear ratio in the rear end axle. Ring-and-pinion selection made easy! Save yourself the headache and let us figure out your ring-and-pinion gear ratio! Just type in your info (example: 5000 RPM), press calculate, and you’ll get the right ratio without the guesswork. Larger tires have the same impact on the drive ratio as using a larger pinion - larger tires produce higher top speed and less acceleration (and they also change your ride height!), so even though you may have the same gear ratio is that other driver, you have a lower effective gear ratio. Here are some points to consider: 1) Tire size – Each standardized tire size has theoretical calculated dimensions called nominal values. Use the RPM calculator to determine what RPM your engine will run based on gear ratio, tire diameter, transmission and MPH. Just type in your tire size, aspect ratio, diameter, old gear ratio and it will calculate it for you. Check out this comprehensive gear ratio and tire size chart from HowStuffWorks. T1 here stands for the teeth number on the. Differential Gear Ratio Calculator Calculate your differential gear ratio from RPM, tire size and desired MPH Ring Gear/Pinion Gear Teeth to Gear Ratio Enter the # of Pinion Gear teeth and the # of Ring Gear teeth to find the correct Rearend Gear Ratio for your Rig! Find New Gear Ratio with New Tire Size Buying bigger or smaller tires?. 73 and the new size upgraded tires are 33 inch. This gear ratio can work on 2dr vehicles or those with manual transmission. Determine the size of drive gear for the speedometer given the tire size is 20 inches and the axle ratio is 3. GEAR RATIO GUIDE FOR LARGER TIRES. Say, for example, you need to calculate the gear ratio for bigger tires. The right side will show the results. New Ratio Needed : 1. The ratio is calculated by multiplying your transmission, transfer case, and ring and pinion gear ratios. One way to compensate for this is to swap out your differential gears. Or, change input variables (engine RPM, axle gear ratio and tire height) to determine vehicle speed in each forward gear. com/_ylt=AwrhcgTnkmFkUGsxTERXNyoA;_ylu=Y29sbwNiZjEEcG9zAzMEdnRpZAMEc2VjA3Ny/RV=2/RE=1684145000/RO=10/RU=https%3a%2f%2fwww. Enter the values on the left and press Compute, the gear calculator will take care of the rest. Divide the New Tire Height (measured in inches or CM) by the Old Tire Height, then Multiply by the Original Gear Ratio: New Tire Height / Original Tire Height X Original Ratio = Return to Stock Ratio. Also calculated is the new gearing you would need in order to return back to your original gear ratio when going to a bigger or smaller tire. Gears from Rocky Road Guaranteed Best Prices on US Made Ring and Pinion Gears! Check out our Powertrax Locker Options We also carry ARB Air Lockers. For a tire size to be considered within a specific RCI, the calculated RCI of the tire must be between -0. Use our gear ratio calculator to find the. RPM: 2806 Stock tires: 29 inch Stock ratio: 3. Your have increased the size of your tire, what gears should you buy? Old Tire Size – 31” New Tire Size – 35” Current Gear Ratio – 3. OhaUse5Niv3KBdNFY1xM-" referrerpolicy="origin" target="_blank">See full list on crawlpedia. Gear Ratio Calculator - Calculate the gear ratio of gears based on their tooth count. The crawl ratio is the number of rotations your engine makes before your tires make one full turn. Just type in your tire size, aspect ratio, diameter, old gear ratio and it will calculate it for you. Per this calculator tiresize. Once all this information is known use the following formula to get the accurate differential gear ratio for the larger tires: Example: The rpm is 2806 at 105 km/h (65 mph), the current tires are 29 inch, the factory. If you don't know, scroll to the bottom of the web page (under rpm/speed table in blue), there's a diameter calculator there, punch in your tire size, copy diameter and paste (you can also compare tire sizes here) -Set your gear ratio for your rear axle (you can also click on compare to see what a gear change will do to your mph/rpm) -If you. Speedometer Check (in MPH) Orig Tire Dia. New Gear Ratio = (2120*34)/ (60*336) = 3. RPM Calculator: Gear Ratio : Trans Gear: Tire Diameter: MPH:. The chart is based on RPM levels at 65 mph (105 kph) and a drive train running at a 1:1 gearing ratio, meaning the. Use our gear ratio calculator to find the effective gear ratio your vehicle will have with a new tire size. Next find the new tire size on the left of the chart and look across to find the RPM closest to your original, the ratio listed at the top of that column will be. Ever wonder what your low-low-low gear ratio is, your "crawl ratio"? You'll need to do a little research by finding out the transfer case and transmission ratios first. Your axle gear ratio determines how many times your driveshaft needs to rotate in order to complete one full tire rotation (a 3. Enter the Axle ratio, A = 3. 56) (see more formulas at bottom of page) The below table can. The right side will show the results. Here's a formula you can use to calculate your vehicle's tire diameter: (CROSS SECTION WIDTH x 0. Use our gear ratio calculator to calculate your new gear ratio and rpm. Use our simple Gear Ratio Calculator to quickly find the correct gear ratio for your ring and pinion gear set. Save yourself the headache and let us figure out your ring-and-pinion gear ratio! Select the value you want to. Find new Gear Ratio with new Tire Size: Now that you have your truck lifted, you want bigger meats. Is it simple to switch the gears out for that ratio?. Speedometer ratio adjustment calculator. The following formula is used to calculate your new optimal gear ratio after installing bigger tires. This calc can be used to find a new gear ratio. -Set your tire diameter. To use our calculator, simply enter your tire size, gear ratio, and engine speed in RPM into the fields provided and click “Calculate. Save yourself the headache and let us figure out your ring-and-pinion gear ratio! Select the value you want to solve for. ” The results will tell you your theoretical top speed in each gear as well as show you what your RPM will be at various speeds in each gear. Once all this information is known use the following formula to get the accurate differential gear ratio for the larger tires: Example: The rpm is 2806 at 105 km/h (65 mph), the current tires are 29 inch, the factory ratio is 3. Use our gear ratio calculator to calculate your new gear ratio and rpm. This gear calculator will get you back to a ratio that's closer to your original. Determine the size of drive gear for the speedometer given the tire size is 20 inches and the axle ratio is 3. 327" And here's a formula that you can use to calculate your vehicle's rear axle gear ratio:. If you want to upgrade your 2017 Ford tires to 35 inches, let’s say your old tires have a diameter of 30. This gear calculator will get you back to a ratio that's closer to your original. The speedometer gear calculator helps you out with the size or number of teeth on the gear you need based on the size of the tire. 235/35R19 Size: 235 Aspect Ratio: 35. 22", a 21" diameter is about 95% of the diameter of a 22", or a 22" is about 5% bigger, so changing tires from 21" to 22" is not as large of a ratio change as changing front sprocket one tooth (8% compared to 5%), thus you can go larger rear wheel …. It is advised to round to the next lower ratio to account for increased rolling resistance, and reduced aerodynamics from being lifted. A gear ratio and tire size chart is essential to making your vehicle efficient. Assuming the gear ratio is 3. The formula for determining an appropriate gear ratio is fairly simple. 10 with 35'' tires or bigger tires? Does the swap is worth? on the gear ratio chart shows that 4. The first thing that people do to get the gear ratio calculator for bigger tires is by using the standard formula. To start, scroll down Top Gear/Tire Diameter/Gear ratio area. Gear Ratio Finder - Find the ideal axle gear ratio for your new larger or smaller tires. Gear Ratio Calculator - Calculate the gear ratio of gears based on their tooth count. 57 Double check that the RPM is really close to the original tire size. Use our gear ratio calculator to calculate your new gear ratio and rpm. New Gear = (New Tire Size / Old Tire Size) * Current Gear Ratio. Transmission gear ratio. Mathematically, you'll have to first calculate the estimated number of tire revolutions, R R R per unit distance (miles or kilometers), like this:. This calculator will get you back to a ratio that's closer to your original. Input your stock and new tires sizes along with your original gear ratio. New Gear Ratio = (RPM * New Tire Diameter)/ (mph*336) So if you want to mount 34 inch tires, now we can calculate the new gear ratio. New Gear Ratio = (RPM * New Tire Diameter)/ (mph*336) So if you want to mount 34 inch tires, now we can calculate the new gear ratio. Save yourself the headache and let us figure out your ring-and-pinion gear ratio! Select the value you want to solve for. Gear Ratio and Tire Size Chart. One way to do that calculation is simply to multiply the Gear Vendors' overdrive ratio of 0. ODR = (Original Tire Dia / New Tire Dia. The setting will work efficiently on off-road adventures with generally tough terrain. Here are some points to consider: 1) Tire size – Each. The left side of the calculator requires all three entries. Determine the size of drive gear for the speedometer given the tire size is 20 inches and the axle ratio is 3. Ever wonder how far off your speedometer is with your new bigger tires? I'm using a simple ratio calculation, so this info will only approximate your corrected speed and depends on the accuracy of tire size diameters (assuming nothing but tire size has changed). 73 driveshaft rotations to turn your tires 360 degrees). 57 Double check that the RPM is really close to the original tire size. ” The results will tell you your theoretical top speed in each gear as well as show you what your RPM will be at various speeds in each gear. The formula for determining an appropriate gear ratio is fairly simple. Using this ratio is ideal, especially if you use a 4. ASPECT RATIO x 2 ÷ 25. These gear sets can be changed out by professionals for either different aftermarket or original equipment gear sets. Find new Gear Ratio with new tire size. Ring-and-pinion selection made easy! Save yourself the headache and let us figure out your ring-and-pinion gear ratio! Just type in your info (example:.