The standard Polaris OEM 8 spoke wheels are:
Front 12"x6" with 4+2 offset
Rear 12"x8" with 6+2 offset
Before I added a RacerTech 2" lift kit I was right at 49" on outside rim bead to outside rim bead overall width. After adding the lift kit I am at 48" wide exactly.
Now the STI HD2 rims referred to above are 7" wide in either the 12" or 14" diameter and both have 6"+1" offset. So on the front if you did run a larger diameter tire than 26" it would likely rub, however if you wanted to run 10" wide tires on all four corners (as some do) the 10" wide tire would put you back to 50" wide in the front. On the right rear the dog gone motor mount can be problematic depending on tire diameter & width. On the rear you could possibly run a 12" wide tire vs. the 10" stock tire in 25" diameter and still be 50" wide. thats what I was told when calling asking "how wide will it be" and of course the follow up you get is, "It depends on other things as well. (lift kits etc.)."
That being clear as mud and with the tire sizes offered by STI I calculate they are referring on the web page detailing the 6+1 offset rims are referring to running either thier 25" or 26" diameter tires in 9" width for front and 12" width for rear. This would theoretically put you at 49" wide in front and 50" wide in rear with that particular setup. STI offers the Black diamond XTR in 25x8x12 & 25x10x12 which is OEM dimensions, or in 26" you can go with 26x9x12 or 14" and 26x11x12 or 14" or even a 26x12x12.
The thing is there are so many possible combinations it can be dammingly frustrating on what tire wheel combo will measure exactly what, will it rub on anything, and will it actually fit through 50" gates.
Since adding my lift kit and verifying I am only 48" front and rear with factory tires and rims (2012 800 LE) it is my intention to go ahead and get a set of 14" rims with the 4+3 offset (STI HD3) and run 27x9x14 on all four corners. I should be 51" or less given that factory rims at again +2 offsets front and rear going to +3 offsets "should" make me 2" wider overall i.e. back to 50" rim bead to rim bead, and by running a 9" tire on a 7" wide rim shouldn't stick out all that far (compared to a 11" or 12" rear tire size). I like the advantage of having all tire rims the same sze, that way I can have a new spare and it doesn't matter which corner it goes on in case of a cut tire or damaged rim.
Like everyone else I dont want to drop nearly $950 on 5 matching tires and rims then not be able to get through some 50" gates when I go riding in different places.
I hope this isn't more confusing than before but the subject is really a head scratcher to figure out what you want vs what will fit and do so via mail order sight unseen on your machine.