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Discussion Starter #1
I have 18X8 rims. I want to know how do you know how wide your tires are. Not the widness if your looking at the tire from its side but if your looking at it from the back. I know that eg: 245 are 24.5 wide from the front but how do you count looking at it from the rear???
 

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Hunh?

Errrrrrrrr......... tires are just as wide in the front and rear of the tire.

Or am I missing something in your statement? Or by "front" do you mean "side"?

245 is measured in mm, not inches if that's what you're saying (Maybe you mean 24.5 cm?). Additionally, the 245 is the tires cross section width, which is to say not tread width but width at the widest point when inflated and unloaded on the recommended rim size bythe tire manufacturer.

Here's some fyi about tire markings:
Tire Size Markings

The tire size shown above is 225/50R16. The 225 represents its section width (tire width in mm). "50" is the tires "Aspect Ratio" (the ratio of the sidewall height to the tread width). The "R" represents tire construction, in this case radial, and the last item is the "16" which represents the rim/wheel size.

Here's a good place to go for tire info:
http://www.yokohamatire.com/csunderstand.asp

All this info and more can be found there.


Cheers

BJ
 

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Discussion Starter #3
What I mean is if your standing in back of the car looking at both rear tires you can see how large they are.I want to know how do you mesure the largness of the tires...
 

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My previous post answers that question friend.

Read it a few times and it might become clear.

I don't think I can make it much simpler.

Cheers

BJ
 

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Drive through some water, and measure the "footprint" left on the dry pavement!

That will give you the width, or what is hitting the road!
 

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But were not sure what he's looking for.

What are you looking for memere?

You could tub it and put really big tires in !
 

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gn300 said:
But were not sure what he's looking for.

What are you looking for memere?

You could tub it and put really big tires in !

ummm.......

getting a little silly now................

Especially for a front driver. :eyemouth:
 

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Discussion Starter #11
I want to know the difference between the section width of 265/35 R18 and 285/50 R18. Because I mesured the section width of the 265/35 and it's about 10 1/4 inches. I wanted to know how much mider is the 285/50
 

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Woober Goobers!
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I would hazard a guess of 20mm wider according to Great White's info above. But then maybe I'm not good at reading and math.
 

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The width of you Rims help determine the width of your tread. You said your rims are 18x8 so that would mean that you tires should be about 8" wide...... and if you upgrade to 18x10.5 then you have about a 10.5 inch wide tire.

To find the actual widht of a tire. Take the first three numbers i.e. 225... Then divide by 10 to convert it to cm, the divide again by 2.54 to get into inches. That migh help you understand it better.

For example 225 --> 22.5cm --> 8.85 inches
 

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Idaho-Intrepid said:
The width of you Rims help determine the width of your tread. You said your rims are 18x8 so that would mean that you tires should be about 8" wide...... and if you upgrade to 18x10.5 then you have about a 10.5 inch wide tire.
well, not quite.

Rim width does effect tire cross section width but it is not quite as straight a relationship as that. It was probably a little slip in your post, but rim width has nothing to do with tread width. Tread width is what meets the road and is a fixed dimension of the tire, cross section is very effected by rim width however. You really need to select the proper tire size for the rim and vice versa. And the tire and rim must fit the vehicle wheel well openings without hitting body or suspension components. It really is quite complex if you want to deviate from stock or close to stock. Best to seek out a professional if you are a little unclear on proper fitment for your vehicle (tire shop, etc). That being said, most tires fit a range of rim sizes and not just one rim.

Ronbo is correct, all things equal, the larger tire on the same rim will be roughly 20mm wider at the cross section width. The tire may actually look a little wider because the tread width will increase as the cross section increases, just the way they are made. There would be little sense in increasing the cross section width and not the tread width unless the manufacturer is trying to make the tire ride softer (much more efficiently accomplished these days with compund and construction). Just remember the numbers on the side of the tire is cross section width and not tread width.

here's a little something I "stole":

Rim Width and Aspect Ratio

TIRE WIDTH
To accurately measure the width of a tire, the tire must be mounted on a rim. Since a tire's section width is larger if the tire is mounted on a wide rim, and smaller if it is mounted on a narrow rim, each tire is measured on a specific rim width.

For example: For tires with aspect ratios from 80 to 50, the measuring rim, also called the design rim, is specified to be 70% of the section width. For tires with an aspect ratio less than 50, the measuring rim is 85% of the section width.

RIM WIDTH
Correct rim width ensures flex at the designed flex point in a tire sidewall for optimum tire performance.

If the rim is too narrow, the flex point moves toward the shoulder area, creating heat buildup in the shoulder, which reduces tire life and could result in failure.

If the rim is too wide, the flex point moves towards the rim area, causing heat buildup in the lower sidewall, which reduces tire life and could result in failure.

Within the acceptable range of rim widths, one can select wider or narrower rims than the measuring rim. Selection of a wider rim, from within the approved range, (T & RA tables) stiffens the sidewall and improves handling at the expense of handling. If carried too extreme, either too narrow or too wide of a rim, it can result in uneven tread/pavement contact pressure causing uneven wear and potentially reduced traction, or increased vulnerability to bead dis-lodgement. Always check with your Dunlop dealer for permissible rim width options.

Wider rims may offer some performance advantages over narrow rims. A wider rim increases the distance between the beads, which results in a straighter sidewall, which stiffens it. This results in quicker steering response and higher cornering forces.

Negatively, the straightened sidewall transmits more road shock to the wheel and suspension, placing greater stress on chassis and suspension parts and delivering a harsher ride. The straighter sidewall exposes the rim, making the wheel more susceptible to damage.

A narrower rim pulls the beads closer together, curving the sidewalls. This increased curvature allows the sidewall to flex more readily over bumps and absorb more road shock during driving. This offers a softer ride.


Cheers

BJ
 

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Don't worry bro, learning never stops.

I learn more everyday myself.

If you don't learn at least one new thing everyday, what's the point of living?

Cheers

BJ
 

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Woober Goobers!
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It's close to Wirdness
 

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MathWiz said:
Now I have Math degrees and not English, but is widness even a word?

Charles
lol, hey mathwiz, try this one on for size. what is the square root of 1 cubed? lol j/k man. widness isn't, but Wideness is. (the property of being wide; having great width)
 
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