Boom!City Racer makes a nice 16" rim which works with the factory hubcaps....if you want to keep the OEM look.
I have also read that the FJ Company are making a similar rim in aluminum. They are pretty pricey though.
16" Wheels / Rims for Land Cruiser FJ40 FJ45 FJ55 FJ60 - https://www.cityracerllc.com/products/16-wheel-for-toyota-land-cruiser-fj40-fj45-fj60-70-series