If a dealer put the wrong size/type of tire on my truck and I have an accident due to this, would I have legal recourse?

Do you have serious injuries ? If not you might have a property damage claim that you can pursue in your county's small claims court. In some states they are called Magistrate/Municipal/ Probate courts. But I would call your insurance agent first and review your declarations cover sheet for the type of coverage you have.

You know there is an issue with the tires, so you should not continue driving on them. Continuing to do so could lead to allegations that you were negligent in continuing to operate the vehicles on improper tires if you were to be involved in an accident. If you had an agreement, try to get them to honor it by giving you different tires. If they refuse, you should do 2 things: 1) replace the tires yourself and keep the receipt; and 2) consult with an attorney in your area. It may be that just a phone call from an attorney would be sufficient to get them to trade the tires.