My front tires rub a little

What are they rubbing on? Do you have standard wheels and tires or something custom? If you have a solid 4wd front axle you should have leaf springs, and the suspension is designed to let the tires go up and down without hitting anything. Sagging ride height won't affect that. 2wd trucks had coil springs and upper and lower control arms. A worn ball joint could let the wheel tip in on top. Still, lower ride height alone will not cause rubbing. There has to be some other cause related to that.

I'm a suspension and alignment expert but not an expert on tire sizes. I just put on what came off. I have to assume this is something new that 's happening. Ride height should not be a factor because the tires would have rubbed before now when the suspension traveled up and down. I'd start by comparing the gap on the two front tires. If one is significantly smaller, look on the top of the leaf spring for signs the axle tube has shifted position. If it has, there is a bolt holding the leaves together that sets the position of the axle mounting pad. GM had a lot of trouble in the '70s with their rear axles shifting from that broken pin.

Also look at the upper and lower ball joints. If one is sloppy it can let the spindle move around. "Caster" is one of the three main alignment angles and it will squirt the spindle forward from the weight of the truck on it.

Sorry for being gone so long.

I don't think raising the ride height is going to be the answer because that only changes the at-rest height. The suspension will still travel up and down over bumps in the road. You're either going to have to put on tires that are closer to what the truck was designed for, or you might check if they only rub when the steering is turned nearly fully left or right. You may be able to fashion some stops to reduce how far the wheels can be turned. Look at how they did it on the back of the lower control arms on the older full-size "B" vans from the mid '90s.

Keep in mind that the over-size tires alone can get you in trouble with a shrewd lawyer or insurance investigator, and modifying how far you can turn the steering wheel is another modification they love to find. They WILL convince a jury that you were partially at fault for the crash caused by the other guy who ran the red light, and they will be right. Anything you modify will adversely affect handling, steering response, and braking and will make you less able to avoid the crash. You and I know that may not be true but they will have a strong argument. Those three characteristics are carefully matched when they are designed in and you can't improve on one without degrading another, otherwise the manufacturer would have done it. With all the ridiculous lawsuits today and the sleazy lawyers willing to take them for a quick buck, you might want to consider going back to the original tire size, or at least something closer to what should be on the truck.