With those rims you can run a 275/40/20 without too much issue. There's a slight chance you may be able to fit something like a 285/35/20 but I don't even know if they make those.

 

like i said i run 305/40s with no issues not even any bulge

 

I'm currently running 265/35's Nitto 555's out back and I have no issues with rubbing at all. I have 6" of backspacing though. I was planning on running a 285/30, but they were just too short.

 

yes but thats with a 3/4 drop not a 4/6. that extra 2" in the back might make a difference.

 

if you have more backspacing on your wheels then your offset goes up as well right ??

 

I ran a 275/35/20 on my 20x8s with 5" backspacing for a while with minor rubbing in the rear. A 20x8.5 with 5.5" backspacing would be about the same so you should be able to run a 275/35/20 and roll the lips and be ok. I couldn't roll the lips since stepside bedsides are composite.

 

i have a stepside as well. i have .5" more backspacing. you think thats enough to avoid the rubbing issue?

 

You have .5" more backspacing, but your wheels are .5" wider so it puts the wheel in the same location. You can actually run them and be ok, but the occassional bump will cause them to rub a little. If you really want to run the 275s, you could cut the rear lips and they will fit, I just didn't want to cut mine.

 

ok thanks for the info!!

 

I have 305/45R22 on my 03 Sierra with a 2'' shackles. I had a friend running 265/30R22 on a 99 with a 4/6. He shaved the inside of the top of his rear fender wells. He still had a lil rubbing in the front, but remember if you ever hit a pot hole you're probably going to scrub and possibly pull the lips of the fenders down, mine actually bent my fenders one time. Every time they scrub up front on that fender lip the tires will get gashes too.