expanding tire size width - JeepForum.com
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post #1 of 4 Old 05-19-2019, 12:53 PM Thread Starter
Kluk Ztopolovky
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expanding tire size width

I wonder what would be the next larger tire size I can install on a new 2019 Wrangler Sport without increasing the diameter of the tire . The stock size is 245 / 75/ 17 and in the future I would like to install slightly wider but the same diameter tire . Thanks.

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post #2 of 4 Old 05-19-2019, 07:30 PM
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P-metric tire sizing is simple once you understand how to decode it: the first number is the width of the tire in millimeters, the second is the aspect ratio, and the third is the size of the wheel in inches. The aspect ratio describes the height of the sidewall, its measurement is the ratio (percentage) times the width of the tire. An example of figuring the sidewall height using the aspect ratio would be in the case of your stock tire, multiply 245 times 75 percent, giving us 183.75 millimeters. To find another tire that is wider but the same diameter, all you need to do is find another width and aspect ratio combination that equals the same or very close to the same sidewall height -- keep in mind aspect ratios normally change in steps of 5 (80, 75, 70, 65, etc). Dividing the sidewall height measurement by an aspect ratio will give you the width measurement you're looking for. Example: 183.75 divided by 70% gives us 262.5 or roughly a 265/70/17 tire. Example 2: 183.75 divided by 65% gives us 282.69 or roughly a 285/65/17 tire.

The overall diameter of the tire is determined by figuring out the sidewall width in millimeters, divide by 25.4 to convert millimeters to inches, then add the wheel diameter to two times the sidewall measurement (remember there's a sidewall on each side of the wheel). Your stock 245/75/17 has a sidewall of 183.75mm, converting to 7.23", so the diameter would be 17"+7.23"+7.23" or 31.46".

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post #3 of 4 Old 05-20-2019, 06:59 PM
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Keep in mind, not all tires are created equal.

In other words, not every 245/75r17 is the same size as the next brand. Sadly some of it is hit or mis.

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post #4 of 4 Old 05-21-2019, 04:40 PM Thread Starter
Kluk Ztopolovky
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Thanks. It is rather complicated but you sir explained that really well and so I appreciate it. I've learned something new today . : ) Have a great day.
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