I am wondering the same thing. I painted my stock 20's with flat black inside the spokes and they look pretty good. Now I just need a beefier looking tire.
I believe what is on there now is a 275/65/20 Goodyear. I have already put the 2" NCD level kit on the front and the tire fit is still pretty close suprisingly.
Just got back from tire store and had 305/55/20 Nitto Terra Grappler mounted on stock rim. We then put it on driver side and noticed that it does fit, but at almost left full lock it is within 1/2 inch of the plastic covering the pinch weld. The stock wheel is a 8" wide which pulls the sidewalls in quite abit, but still looks good. Bottom line is I think this will work for everyday driving and still look good. With everything said, I am selling all 4 20's custom painted with the stock Goodyears on them and only 6K miles for $1000.
305/55-20's look really nice on the Titan if done right. Calculated they are only 1/4" taller than the 20" tires that come stock on some 08 titans. They are about 1.25" wider than the stock option though. You can mount them on the 8's but you really shouldn't. Tire manufactures do not recommend mounting them on a wheel less than 8.5" wide for safety reasons. Ideal rim width for a 305 is a 9.5.
Im running 305/50/20s lowered and no rubbing whatsoever. Forgot my rim width. prob 8.5 or 9, but they ballon out a bit. works awsome and no way to curb the rim
If you want super sticky tires comparable to the BFG KDW2 but dont wanna pay 300+ a tire, take a look at the General UHP's in this size. Thier [email protected]! (not in these pics though, these capitals are junk)