A 2in Diameter Rod Is Reduced to a 15 in Diameter Rod Then Reduced Again to 1 in Calculate the Cw
Thinking near changing the size of your tires?
Yous're not lone—people run larger wheels and tires for aesthetic purposes. Nosotros've also seen guys reduce the overall size of their tires for various reasons. However, there are some serious consequences to any changes to tire diameter.
Tire diameter, along with rear-axle gearing, plays a role in the final bulldoze ratio, which in turn affects acceleration and overall performance. For example, a Camaro that has decent acceleration with a set of 26-inch tall tires and 3.55 rear axle gears becomes a domestic dog with 29-inch tall tires and the same gearing. That'due south why it'southward important to compare final drive ratios with different tire heights before making whatsoever changes to tire diameter. By doing so, you can determine the axle gearing you'll need to employ with your new tire diameter in order to maintain (or raise) functioning. You'll need three figures to do this: your vehicle'south current rear axle gearing, the bore of your existing tires, and the diameter of the tires you want to use.
Determining Current Tire Bore
The easiest way to determine tire diameter is to call your tire dealer and enquire for information technology—easy, but not e'er an option. The 2d way is to use the following formulas and figure things out yourself. Please note that these formulas are for metric-rated rider and lite truck tires. Slicks, large off-road, and some larger, Pro Street style tires are already rated by diameter, and so you don't have to practice any computing for them.
We will exist using a P235/60R-15 tire every bit our example: 235 is the section width, 60 the attribute ratio, and 15 the required bike rim diameter. Hither is the basic formula:
Tire Diameter = two 10 (section width/25.four) ten (aspect ratio/100) + rim diameter
When you plug in the values from our sample tire, the formula looks like this:
Tire Diameter = 2 ten (235/25.4) x (60/100) + 15
At present, allow's practice the calculations:
Tire Diameter = two ten (ix.25 x .60) + 15
Tire Bore = 2 x 5.55 + xv
Tire Bore = 26.1 inches (round down to 26)
Calculating Effective Drive Ratio
One time you decide the diameter of your sometime tires and potential replacements, you tin compare the event of new tires on the terminal drive ratio. For instance, if you have 26-inch tall tires with a 3.55 gear, and you want to go to 28-inch tall tires. To calculate the constructive drive ratio of the new tires, multiply the diameters together, and then multiply that figure by the gear ratio equally follows:
26/28 = .92857142857
.92857142857 x three.55 = 3.2964 or 3.30
Every bit yous tin can see, the larger tires reduce your terminal drive ratio to 3.30—a measurable deviation. You tin can too do this to make up one's mind the consequence of smaller tires on your concluding bulldoze ratio.
Calculating Equivalent Bulldoze Ratio
At present that you know that 28-inch tall tires reduce your final bulldoze ratio, you can calculate the gearing need to friction match the performance of your original 26-inch tire/three.55 gear combination. Outset, split up the new tire diameter by the original tire diameter, then multiply that figure by the original (3.55) gear ratio:
28/26 = 1.0769230769
i.0769230769 10 3.55 = 3.82
With 28-inch tires, you would need a 3.82 rear-axle gear to match vehicle performance with 26-inch tires and 3.55 gears. Since a iii.82 gear is not offered for most rear axles, you volition need to cull a gear betwixt 3.73 and 3.90 to get close to the optimum.
Source: https://www.onallcylinders.com/2015/07/30/tire-math-calculating-the-effects-of-tire-diameter-on-final-drive-ratio/