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Discussion Starter #1
I saw this guy's Tundra w/ some pretty sweet tires at work the other day, he had BFG ATs that were 285/55/20. I know that's a big arse wheel and our X won't take it, but what about the 285/55 part? Now that I put a lift on, my 265/75s look just a little too small. 285 means taller and 55 is the width, right?
 

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Nope.

285 is the width in mm
55 is the ratio between width and sidewall height.

Just saying 285/55 means nothing, you need the wheel size int here too.


EDIT:
A 285/55R20 tire is 32x11.50x20
 

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TXterra37 said:
I saw this guy's Tundra w/ some pretty sweet tires at work the other day, he had BFG ATs that were 285/55/20. I know that's a big arse wheel and our X won't take it, but what about the 285/55 part? Now that I put a lift on, my 265/75s look just a little too small. 285 means taller and 55 is the width, right?
The X will take a 20" rim, some of the guys over on ClubFrontier are running 20" rims also.
 

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Discussion Starter #6
So, would 285/55/16 work? My big concern is that I got 265/75/16 before I put my lift on (see my signature for details) and now they just look a little too small. I was thinking of going 285/75/16 but in fear of all the horror stories of balancing, rubbing, etc. And I want to stay w/ the BFG ATs, which they only make the MTs in the 255/85/16 right? So I guess I'm basically looking for ATs that are...taller? Do I need to switch to metric size?
 

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A 285/55R16 would be a 28x11.5x16 tire. My guess, no one makes that size. And what you are talking about is metric size.

33x11.50x16 is in inches
285/75R16 is in mm
 

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Didn't you just get the 85 and 55 switched up?

255/85/16 is a 33.3" tire.

285/55R16 is a 28" tire.
 

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This might help.

The 31x10x16 is actually very easy to unserstand. That would be a 31" diameter tire, 10" wide and fit a 16" wheel.

285/75R16 is confusing as all get out in the US world of non metric standards.

285 is the width of the tire in mm
75 is the aspect ratio of sidewall height vs width
16 is the wheel size in inches.

So....to convert 285/75R16 into the inches (which is what most people look for).

To find the width of the tire in inches.

25.4 is how many mm per inch.

285/25.4=~11.2


To find the height of the tire in inches.

285*0.75=213.75mm

The height of the sidewall is 213.75mm Since we want to find the height, we need to times it by 2 (since there are two sidewalls in the diameter of the tire)

213.75*2=427.50mm

Now we conver this to inches.

427.50/25.4=~16.8in

Now we need to add the wheel size to complete the height.

16.8+16=32.8"

So...a 285/75R16 tire is a 32.8x11.2x16 or very close to a 33x11.5x16 which is usually what everyone refers to them as.


I hope that makes some sense. If you do a search there are calculators to do the conversions for you. I find it easier to understand if I know how it's calculated. You now also probably know more about tire sizes than the folks selling them at the local tire stores.
 
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