* I've had to change tires on my tandem trailer many times (though none so far on my 4x8), at various angles, on various surfaces, in various weather conditions, while towing my race car (or a project car). Sometimes you can't choose when or where you need to change it, so I gradually acquired several types of jacks to help do the job (several times needing a combination of them). Though I no longer have the tandem trailer, nor the race car, I still carry several jacks in my '04 Chevy 2500HD tow vehicle, though my 4x8 trailer doesn't need most of them (the truck might).
* I have two pipe-stand stabilizers on the rear of my 4x8, each able to hold up to 600-lbs, and a scissor jack mounted on my single beam tongue, capable of a 5000 lbs lift, so I could easily change a tire using them alone. My preferred jack was a bumper jack from my '66 Chevelle race car, but it went away along with the car. I'm sure my collection of jacks could fill-in, if ever I actually need to change a tire on it. I don't actually foresee needing to, since I no longer use may-pop Chinesium ST tires on the trailer, but have LT tires, now.