What is Rim Width? How Wide or Narrow Should Your New Wheels Be?

Feeling a little overwhelmed by all the wheel choices available for your vehicle? All the listed options are compatible wheels, but there are some nuanced differences in how offset and width affect wheel fitment.

What is rim width and how does it affect what tire size(s) can be used?

Wheel width is measured from the inside of one wheel flange to another as diagrammed below:

For example, my Original Equipment BRZ wheel is 17" in diameter and 7" wide. If you're not sure how wide your wheel is, flip it over and look at the back of the wheel for a marking such as "17x7JJ" or something similar with the second number being the width. Since a tire sidewall and bead can only stretch so much, each tire will have a recommended rim width range, so wheel width dictates what tire sizes you can choose. Going back to the BRZ example, I can't mount 245/40R17 on my O.E. BRZ wheel because it's too wide; nor can I mount 17x9 on my O.E. 215/45R17 because the tire is too narrow to safely fit on the rim.

What is the advantage to choosing a narrower wheel?

As you filter down to wheel widths that fit your ideal tire size's recommend rim width range, you'll sometimes find that your preferred wheel style is available in multiple widths. The primary advantage of choosing a narrower wheel is that it creates a buffer between the edge of the tire and a curb. Many tires have rim protectors, but a rounded sidewall of a wide tire on a skinnier rim protects even further.

What is the advantage of choosing a wider wheel?

What if you haven't had bad luck with scuffed rims in the past or rarely have to parallel park? From a performance standpoint. you're better off picking a wider rim because it gives you a slightly larger contact patch and optimizes steering response. 

Finally, there's a subjective aesthetic assessment to be made. It seems like most drivers prefer the flat, horizontal sidewall contour of a fatter rim and skinnier tire on sporty cars. They are accustomed to the rounded sidewall contour of fat tire and skinny rim on trucks and Jeeps. 

Comments

Monday, May 15, 2017 by Kevin d

I need advice on tire sizes for the Subaru BRZ, I want to go wider in the rear with stock suspension, just want to play it safe and make sure I get advice from a professional
Tuesday, May 16, 2017 by Cy

Kevin,

Since we ship most of what we sell we’re very conservative when we look at the risk of rubbing. So I would also recommend getting anecdotal feedback from other FT-86 drivers who are actively experimenting with different sizes at:

http://www.ft86club.com/forums/forumdisplay.php?f=24


That being said, with our extremely careful assessment we see 255/40-17 and 265/35-18 as the widest standard fit sizes on wheels of the proper widths and offsets.

Thanks.

Cy

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