I think the MR-1s come in a 17x8 with 4.75" backspacing for the Jeep bolt pattern (I considered those when I was wheel shopping). That's the same backspacing as my Rugged Ridge wheels so take a look at the pics and that's how much you can expect them to stick out on a 12.5" wide tire.

I have Toyo AT IIs in 35x12.5x17... mounted and under the Jeep they measure just under 34". Like Cavallini said they're E rated, but I barely notice a difference from the D rated Cepeks I had on before the AT II. For how aggressive the tread pattern is I think they ride awesome on the highway, and the price is insane on them... the 35s cost $50 less/tire than my 33" Cepeks. Great in the snow as well (haven't had them in the mud yet so no help there). Would definitely check them out.

 

So the the 285/75's are closer to 32's?

 

My 315/70/17 Duratracs are about 34" and I'm running them at around 28psi

 

I just want a true 33" tire, so if anyone knows of a size that's a true 33 let me know

 

33x12.5 is a 33" tire

 

I know, but but some of these metric sizes are a bit more tricky.

 

I know, but some of these metric sizes are a bit more tricky.

 

I've got 285/70/17's. At 30psi, they're sitting at 31.5" tall. They're the Firestone Destination AT. Just to give you some insight

 

My 285/75R17 Toyo A/T II are a little over 33 when mounted.

 

To help you understand tire sizes a little better here's a quick lesson.
For an example we'll use a fairly common tire size of 285/70/R17.

We'll first label the parts as follows:
285/70/R17
_^__^__^
_A__B___C

A- This is the width of the tire in millimeters. The conversion is 1"= 25.4mm so for our example: 285/25.4= 11.22" width.

B- This part is the "aspect ratio" of the tire and is a relation of the tire's width to the sidewall height of the tire. In our example it's '70'. This means the sidewall height is 70% (.70 in calculation) of the width of the tire. That means the sidewall height is:

11.22 x .70= 7.85"
BUT there is a 'sidewall' both above and below your wheel when measuring height, so you must multiply this by 2 when calculating the tire's overall height.

C- This third piece is simply your rim size. So, for a final calculation of a tire's size, you add this to the total from part B.

In conclusion, a 285/70/R17 equates to 11.22" wide and is (7.85x2)+17"= 32.71" tall, or basically equivalent to a 33x11.50R17 if we called it a standard size.

How about one more example, 265/75/R16:

Width: 265/25.4= 10.43"
Sidewall: 10.43 x .75= 7.82"
overall height: (7.82" x 2)+ 16"= 31.64" tall. Basically, a 32x10.50R16

This method of finding a tire size will work for every metric tire size out there!

NOTE:
It should also be mentioned that different manufacturers' tire sizes will slightly vary from these calculations. Its usually a very minor amount but it's still there none the less. For this reason I recommend everyone looking at tires to go to the respective manufacturers web site and look up the exact specifications they list for the tire before buying a set, or to compare tires between different manufacturers.

Hope this helps and that you can calculate tire sizes without having to be reliant on a program.