I'd go with the taller and skinnier 285/70R17's and use your stock wheels than the smaller and wider 33x12.50R17... which I'd recommend wider wheels for being that they're 10-ply and less forgiving on a 17x7.5" wheel. 99% of the time for the general population, a wider tire will hurt performance in every conceivable way off-roaders use their trucks.

 

That's forum folk-lore. You have at least 1" of adjustment up and down with the stock torsion bar keys. If you need more lift, body lift it. Cranking up the torsion bars more than 1-2" kills front suspension parts.

 

305/70R16 on a t-bar key changed on my truck did not rub. Did a body lift and running 35"s with no rubbing once so ever.

So your anser to your question is no it will not fit on stock keys stock height, change them and do a body lift and put 35"s on it.

 

Its not folk lore. Ford keys are indexed differently and do allow for more adjustment upwards. Maxed stock keys ride harsher than the Ford keys will at the same height; granted, either way will stiffen the ride some. I am aware that cranking more than 2" will create more stress on the front end components; I was just stating a way of providing more clearance. The best way without going with a lift kit is to use the GK bars off a 2500 swapped front to back since the half ton bars will sag over time being cranked. The only thing is that going that way only nets about an inch to 1.5 inches of lift.

 

The folk-lore I refer to is the ridiculous following of guys on the forum thinking they must change out to Ford keys for ANY torsion bar adjustment...that's simply not true. The only time Ford keys can help is if the torsion key bolt runs out of adjustment. I caution anyone cranking their torsion bars that far.

I will also give you the opportunity to edit your post, afterward I will then edit my quote of your post to reflect your changes.
Answer me this: If you max the stock torsion bar keys out to a spring rate of 400lb/in, for example, and crank the Ford re-indexed keys to the same spring rate of 400lb/in, which setup will ride the roughest? Hint: It is a trick question.

 

You can clear 33x12.50x17's with a torsion bar adjustment. Some trucks can get it with stock keys, others can't. You can run them on stock wheels, just watch air pressure. There are lots of tires in that size(and some in the same size just metric), here are a few, and there actual heights
1.Super Swamper SSR Radial=33.4 E load
2.Mickey Thompson Baja MTZ=32.8 D load
3.Mickey Thompson Baja Claw Radial=32.5 D load
4.BFG Mud Terrain KM2(305/65/17)=32.8 E load
5.BFG All Terrain T/A KO(305/65/17)=32.7 E load
6.Cooper Discoverer STT=32.76 D load
7.Dick Cepek Mud Country=32.8 D load
8.Dick Cepek Crusher(305/65/17)=33.1 E load
9.Nitto Mud Grappler=32.95 E load
10.Pro Comp Radial Mud Terrain=32.5 D load
These are the main ones I could think off. There are other, but this is a good sampling.

 

I had Ford keys with the 3" blocks in the rear and was running 33x12.5x17 MTZ's with no rubbing at all. I put the 3" blocks in and put cranked the Ford Keys to level with the rear. You can probably run the 33x12.5 with stock keys but you will have to trim the valance.

I have cranked the stock keys and cranked Ford keys and havent had any problems with my front end yet. I dont do a whole lot of offroading but its all in how you use your truck.

 

These are 285/75/16s on a 16x8 wheel... with F150 keys and AALs... you will be ok with 285/70/17s on a Z71 with just a tbar crank

 

Both beastmode and clean's trucks are fine examples of the valance trimming. Just that little corner.

 

Well I got em on and rubbing more than just the valance LOL. It's rubbing front and back on the wheel well but i'm gonna try and do some triming tomorrow if it's not to cold. Btw I also cranked the bars almost to max.