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      08-17-2018, 07:20 AM   #16
Ali-E90
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Drives: 2007 E90 323i (Cdn)
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Quote:
Originally Posted by TheMidnightNarwhal View Post
Yeah wheel sizes and tire sizes are really the only thing that confuses me so much.
Agree it can be confusing at first...

Once you get it it's not that bad though...

If tire size is 235/35/19, this is what it means:

235 = tire width measured in mm
35 = sidewall height measured as a % of width (in this case, 35% of 235mm; this is why a 235/35 tire is shorter than a 255/35 tire)
19 = diameter of rim, easy

As you change tire and rim sizes, the goal is to keep the overall diameter the same.
So whether you change your width, or rim size, it's the second number (sidewall ratio %) that changes to achieve a diameter the same as original.

Hope that helps.
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