Horizons measured out at 46 (!) for me on 25 ID rims, the tread seemed like they would last a while, its pretty thick. I wasn't a huge fan of how they felt, but that's probably because I was coming from 32s!
If going tubeless and you have the budget, the SBHs are still the gold standard for 650x48 slicks (not what you asked, I know!)
Cheers,
Collin, Sactown