Tire is too wide.

 

so we got half and half lol but i am gonna do it anyways, just gonna run low psi which is wat i always do anyways no biggie and lets see this goes

 

 

^^ I'm with GotHemi on this one. Your def pushing the limits and I think you'll find yourself wearing out the middle regardless if you go less on the air pressure. Then if you go too low, you'll be wearing out the outer edge of the sidewall. Just not a position I'd put myself in to go a smidgen wider. There is no happy medium for a tire that is too wide for a rim. It just cannot hapen. It will either be convex or conave. Either one will wear prematurely not to mention the loss of traction from improper footprint.
Can you go that wide without rubbing on the upper control arm with just an 8" wide rim???

The rule of thumb for the difference of 4 is just that, a guide. You really need to check out the manufacturers specs for what they reccomend. Some are a little diferent than others depending on the material make-up and design of the tire.
Just for a reference so you get an idea...The reccomended rim size for a 285/70 size tire is actually an 8.5" wide wheel, so your actually running yourt current set-up on a little skinner wheel than what is reccomended. Now, you want to go 3 sizes wider.
The widest tire I would go is 295. So, unless your current tires are worn and need replacement, I'd say spend your money elsewhere.

 

And also if you run your pressure that low, you will have awful gas mileage with that low of pressure, we are talking 2 mpg less at least probably, the resistance just from a well aired wider tire is enough to take away a little bit, to have a wider tire aired down it will destroy your gas mileage if you could even pull it off.

 

i got 1.5" hub centric wheel adapters so it dont rub the uca, but i notice many guys on here have stock rims with 12 inch wide tires, i have tires on there right n ow that are 11.3 inches wide, is that .7 of a inch really gonna matter

 

and i wont run to low psi, but like that dude said before, i have heard of the 4 rule, where u have 4 inches from rims to tires....