Ford F-150 15" rims vs 17"rims

I currently have 17" rims on my 2004 ford f-150 (small v8) and pull a dual axle trailer w/2000 lbs of equiptment. Can I change to 15" rims and what size tire do you recommend. Currently running 235/70/17

Why would you want to? You’re not going to come out ahead when replacing the tires, since you’ll still have to use tires that are the same overall size anyway.

would the 15" rims even clear the brake rotors/calipers?

Towing? Get the LT series tires instead of the P-rated ones. You might be able to switch to LT245/75R16. The 2004 probably did not come with 15" wheels.

The tires you have on there now are not good for towing - not enough load carrying capacity.

Look at the tire placard on your vehicle. It will tell you the tire size that came on the truck. Then check with Ford to find out the towing capacity of the truck. If the trailer is within the towing capacity listed by Ford, then the tire size listed on the tire placard is adequate.

If the trailer exceeds the towing capacity of the truck, then it would be best to get a truck that is larger.