My Jeep and trailer do run the same size tires. The wheels are also the same size and the same brand (Eagle Alloys), but I didn't want that perfect matched look. My trailer is black so I like the look of black wheels on it better then the polished aluminum that I have on my Jeep.
To start with, I did build my Jeep up with an eventual trailer in mind, and that they would share the same size tire, simply so that one spare works for both. I've heard from guys like
Andrew St.Pierre White when running through the African bush, just for his one 4x4 alone he carries
two spare A/T tires. Well I'm not running through the African bush, and I'm pretty confident in having just one spare Goodyear MT/R for what I do. That's also less weight to carry, which weight is always something I consider driving a short wheel based Jeep with a 4.0 I6.
And, even though I've replaced most of my Jeep's suspension and can go higher in lift and tires size, I'm only running 32" tires. Which for a Jeep TJ, most lifted TJs tend to run 33s or 35s. I can run 33s as it is now, and with flat flares and keeping the same springs I could run 35s. But again, I was thinking of a trailer, and more then 32" on a trailer would IMO be even more overkill, and more then 32" on my Jeep is again more weight. 32s are just right for my setup. The trailer follows me about anywhere I think it's safe to take a trailer, and isn't too high up in the air to worry about center of gravity issues.
I will say that having oversized tires on a trailer is a bit of guessing game about air pressure. I don't want it too low on the highway, but too high either to where the trailer bounces. They're both level with each other and run great together, which stability is always been something I've kept in mind as well as I drive down the highway to my off-road destinations. The trailer tows great and I'm very happy with it. It's given new life to camping and exploring, simply due to being able carry more then what fits in the back of a Jeep, let alone the RTT on the trailer. (No more ground tent!)
I guess I said a lot there, but just some general thoughts to share.
My setup: