by Justan Brandt
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If your vehicle has low profile tires, which offer a small amount of side wall height, and you want to replace them with ones that have higher side walls, you will need to decrease the size of the wheel diameter. Most professionals suggest that your new tire and wheel combination be within 3 percent positive or negative of the original equipment.
Tire size reading
Look for the size markings on your tire. An example: 245 / 50R19
Consider the first number. “245” represents the width of the rim, in millimeters, at the widest point.
Look at the second number. “50” represents the height of the sidewall of the tire, from the rim to the tread, as a percentage of the width of the tire. In this case, the height of the tire would be 122.5 millimeters, which is 50 percent of 245 millimeters. This is also known as a tire series.
Consider that the final number “19” represents the diameter of the wheel, in inches, on which you intend to mount the tire.
Do the math
Calculate the overall height of the tire, in inches, using the following formula: ((Width / 25.4) * percent of sidewall as a decimal) * 2 A 245 / 50R19 tire would have an overall tire height of 9.64 inches: ( (245 / 25.4) * 0.5) * 2).
Combine the total height of the tire with the diameter of the wheel to reach the final diameter of the wheel and tire combination. Using the example above, add 9.64 to 19 for a final diameter of 28.64 inches.
Keep the 3 percent variance rule. You can install a new wheel and tire combination that has an overall diameter of 27.78 inches to 29.50 inches.
- Make sure the inside diameter of your new wheels does not account for the brake calipers and is the correct width and offset for your vehicle as well.