I have an '11 5.0 4x4 with 3.55s, and came from the stock 235/75R17s when they wore out. I went with 285/70R17s as they are an easy direct swap for the stock tires on the stock rims with stock suspension and no modifications are needed.

The difference from the 235/75R17s is modestly noticeable. The truck sits an inch higher and the wheel diameter is 2" larger, which looks absolutely appropriate, and what Ford should have rolled out of the line at River Rouge instead of the weeny little tires they shod my truck with. The larger tires throw the speedometer off by about 5% (3-4 mph at highway speeds) and causes the already overly aggressive to upshift transmission shift logic to be a little worse, but a little more right foot counters that well. You could regear to 3.73 or better yet 4.10 but you could also get a tuner to shift the shift points up by about 5-10 mph for the same effect. The fuel economy meter is off by a bit too, but you are driving a V8 truck weighing close to three tons with almost 400 hp, and gas is about two bucks a gallon, so an mpg or so difference shouldn't give you much grief. Else you'd drive a Prius with tires about the same size as the steering wheel in your truck.

Going from 32.1" 275/65R18 tires to 32.8" 285/70R17 tires will yield no discernible effect on your truck as they are a whopping 5/8" taller and 3/8" wider. The 285/75R17s will be a little taller and from what I have gathered (and why I went with the 70s rather than 75s), you may need a level kit in the front to keep from rubbing with those tires.

Personally I'd stick with your stock sized tires if you are any bit happy with them as going to any 17" tire requires new rims. If you want something larger, get something noticeably larger like 35s and do the lift required to run them.

 

thanks for the response. I ended up going with the 285/70r17 a while back, just never updated the post.

 

Looks great, love the Raptor wheels.

 

Thanks! I figured they would be a good match with the color and trim on my truck. The width and offset is perfect for my liking as well. They aren't quite as tucked in the wheel well as the stock wheels but they don't stick out too far. I noticed a very slight decrease in throttle response and mpg but that's it.

 

I have the same wheels and tires. Did you use a leveling kit?