Bike24.com has these fat, fat Schwalbe G-One HT Speed Evolution tubulars with a "basketball" tread in 30mm width for a great price:
https://www.bike24.com/p2196555.html
I bought 4 and immediately had to try them on my Velocity Major Tom rims and they are a match made in heaven. Unfortunately for me my wheels are 130mm rear hub, rim brake and all of my road bikes seem to run out of clearance with tire widths much wider (or taller) than 27mm.