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Discussion Starter · #1 ·
So the stock 32's are 255/75/17's (32.06" by def, but I measured at 31.5" inflated and mounted). Are spacers required to fit 285/70/17's (32.71", which I am imagining will also "shrink" .5-1" when mounted)? I know strictly going by the numbers on the side the answer is likely yes, but considering real world shrinkage, is this still a factor?

Thanks
 

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I AM THERE4 I JEEP
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The shrinkage isn't your problem its the width on stock wheels with low backspacing. You will need 1.5" spacers to run them if you mount them on your stock wheels.
 

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Discussion Starter · #3 ·
So shrinkage is only vertical and not horizontal?
 

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So shrinkage is only vertical and not horizontal?
The width of the tires will not shrink if anything it will expand slightly. The weight of your jeep compresses the tire making it shorter but also wider. The issue that will cause you problems still is mounting anything larger than 32" tires on stock wheels.
 

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Discussion Starter · #5 ·
The issue that will cause you problems still is mounting anything larger than 32" tires on stock wheels.
I think this is where I am confused. If the width (backspacing issue) is the problem, what does height (32") have to do with the problem? Shouldn't the aspect ratio (the second number "XX" in a tire size equation 275/XX r17) be considered to determine if it is too wide with not enough backspacing?
 

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The tire size you mentioned going to is wider and taller than your stockers. The height isn't that big of a deal unless you wheel it in some places and it will come into contact with your flares. The width of the new 33" tires will come into contact with not only your sway bars but your air dam and possibly more. When you mount a wider tire on your stock wheel, the larger width of it is pushed in towards the jeep because the stock wheels have low backspacing causing the tires to stay tucked under the fender flares. You mount a bigger tire on it and your essentially shoving a 11" foot into a 10" shoe. Kapeesh?

Check out selling your stock wheels and tires together and then move down to either a 16 or 15 inch wheel with 33s. If you go to 15s then the cost of new tires/wheels will nearly pay for itself.
 

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If you are wanting to not change wheels or add wheel spacers, have a look at the 255/80/17 KM2. They are 33" tall, but only 10" wide. Also known as "pizza cutters". lol. Here is a pic to show the difference between the 255/80 KM2 and the stock Rubi 255/75 KM. Obviously these Rubi tires have quite a few miles on them, but still.


And here they are mounted up. Keep in mind, this Rubi has a heavy front bumper as well.


And why there are called pizza cutters. :D
 

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I remember these pics from back in the day. Those worn tires are nearing bald and "pizza cutter" is definitely accurate for 255/80/17s. Don't go that route, you will always regret it.
 

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On a different note though,

Manufactures measure the height of there tires at proper inflation. You cannot compare a tire mounted and inflated to one thats not. Sidewalls arent correct, the foot print isnt acurate because of no load and no inflation.
 

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gluestick said:
I think this is where I am confused. If the width (backspacing issue) is the problem, what does height (32") have to do with the problem? Shouldn't the aspect ratio (the second number "XX" in a tire size equation 275/XX r17) be considered to determine if it is too wide with not enough backspacing?
The first number is width, the aspect ratio determines the percentage of the width that is equal to the hight off the rim so if it's a 255/70/17 then 70% of 255mm is sticking up off the rim. If you want to find total height, it's just double the aspect ratio*the width measurement(first number) and then add the rim size(3rd number). You'll have to convert units tho to get it in inches

If you are talking about wheel spacers, which only are needed for wide tires(tall tires need a lift) then you should really only worry about the first number
 

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I remember these pics from back in the day. Those worn tires are nearing bald and "pizza cutter" is definitely accurate for 255/80/17s. Don't go that route, you will always regret it.
Some experts would differ with you on that:

Expeditions West: Tire Selection for Expedition Travel



I've settled on BFG MT T/A KM2s in 33x10.5x15 as my next tire based largely on that article.....
 
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