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Anthony 05 GT

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This is not directed to everyone, but a few for sure.

I notice a lot of guys think that different wheel sizes affect how much the tire/wheel combo will fill the wheel wells on cars. I'm referring to stock, factory sizes, not some crazy combo you might buy and install.

Whether you buy a car with 17's, 18's, 19's or 20's....they are all between 27.03'' and 27.66'' tall which is virtually the same overall height. Not trying to be rude, I just see that some do not know this and that's why I'm posting this in the general forum, not the wheel and tire forum. Simple fact is, you may have a 20'' tire, but it has much less sidewall compared to a 17'' tire.

I have some examples here on 2015 Mustang stock tire height comparison.

265/35/20 is 27.30'' tall

255/40/19 is 27.03'' tall

275/40/19 is 27.66'' tall

235/50/18 is 27.25'' tall

235/55/17 is 27.17'' tall
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Old 5 Oh

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The diameter makes little difference on the factory choices, but the width is indeed important. The 8" rims tuck into the wheelwells more than do the 9"-10" rims. The PP wheels are nearly flush with the fenders, which is not true of the 8" rims.

I haven't seen a set of 17x7's live, so I'm not sure how those are different.
 

GoBlues38

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it is simple math. most people don't know what the numbers on a tire mean.

265/35/20

265 = tire width in millimeters
35 = height of tire as a % of width
20 = inside diameter of tire to be mounted on a rim

knowing these numbers, you can easily figure the height of your set up

265 x .35 = 92.75 milimeters / 25.4 = 3.65 inches x 2 = 7.30 + 20 = 27.30 diameter
 

RobbieFrazier

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This is not directed to everyone, but a few for sure.

I notice a lot of guys think that different wheel sizes affect how much the tire/wheel combo will fill the wheel wells on cars. I'm referring to stock, factory sizes, not some crazy combo you might buy and install.

Whether you buy a car with 17's, 18's, 19's or 20's....they are all between 27.03'' and 27.66'' tall which is virtually the same overall height. Not trying to be rude, I just see that some do not know this and that's why I'm posting this in the general forum, not the wheel and tire forum. Simple fact is, you may have a 20'' tire, but it has much less sidewall compared to a 17'' tire.
I understand your frustration, Anthony, and I actually feel the same in most cases. However, there is another perspective to consider. Keeping the overall outside diameter of the tires, the wheel diameter can still have the effect of visually filling the wheel wells. Since tires are black, they can appear to be part of the gap in the wheel well.

Personally, I think 19" or 20" wheels fit the S550 perfectly (i.e. filling the wheel well). Wheels below 19" look too small (dark gap appears too large) and I'm sure wheels above 20" would look too large (dark gap would appear too small, although I haven't seen such a setup yet).

Just some food for thought.


35 = height of tire as a % of width
Correction: the ratio represents the height of the sidewall as a percentage of width. Your example accurately reflects the math, but the verbiage is a bit misleading.
 
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Anthony 05 GT

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That is true about the larger wheel size ''appearing'' to fill more of the gap.
 

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So your saying my 18 inch stock wheels and tires should fit?
 
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Anthony 05 GT

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Damn you're smart!
 

Project Whitemare

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Anthony, what's up brother. This is S197 GT from over at S197. Totally different group here. These guys don't seem to be too into tech info.

I think you probably already see that.
 

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Anthony 05 GT

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Anthony, what's up brother. This is S197 GT from over at S197. Totally different group here. These guys don't seem to be too into tech info.

I think you probably already see that.
Hey bro, what's been going on? Definitely not trying to be a wise ass, but after seeing posts that seem to assume 20's are taller than the smaller wheel sizes (with tires) I figured I'd offer some facts on the matter.

I hope at some point the wise guys will acquire and retain enough information to actually help people on this forum. I've been a tech long enough to know that sometimes even a young inexperienced cat might show me a thing or two.

Good to here from you, what are you driving? I'm keeping my '05 which is fair weather only...need a new one and it's coming.
 

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Very nice and informative thread. Many people do not know that by getting the proper tire size you can have the same overall diameter. Thanks for posting :thumbsup:
 

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You forgot OFFSET. (It applies to tire RIMS) and is an important part of choosing a rim and tire. I am not 100% sure of the tech details but I believe OFFSET is the amount the rim is set off from center, of the mounting point to the rim/suspension. A zero offset would have a mount point in the center of the rim, a negative offset would actually make the tire appear narrower in the wheel well and a positive offset makes the tire appear wider and push it out further in the wheel well??????:)
 
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Anthony 05 GT

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I didn't forget offset or backspacing either for that matter, but you are right...there are many factors that affect how a wheel will look on a car. This thread is intended to address the wheel diameter issue.

Here is a link to address offset and backspacing since you brought it up.

http://thesquealingtire.com/wheel-offset-and-backspace-explained/
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