Brain, here is a wicked setup with a 1.5" level. Actually the 1.5" level works the best on the 09-10 trucks. Anything more sits nose high and you need a block or leaf in the rear.

https://www.f150online.com/forums/20...grapplers.html

If you dont want to do a level, you should still be able to fit a 33" tall tire, but I would stick with a 285" series. Not sure on the aspect ratios for a 17" rim though.

My 305-55-20 (33x12.5) tires rub both on stock 20s and aftermarkets -12mm OS and 2.5" level

EDIT*** Here is a link that will help.. toyo specs page. Looks like 285-70-17 (32.7" tall) or 285-75-17 (33.8" tall)<<<< this will be too large with out a level and will rub.

http://toyotires.com/tire/pattern/open-country-at

Go to "sizes and specs" tab