39-40" all-terrain tires?

Looking for 39-40" tires on 18" or 20" wheels.

I tried searching as many brands as possible but maybe there are some I haven't picked up yet or some non-DOT or race tires that are basically ATs. If all else fails, I'll give up on the AT search and just go with 40" IROKs on 20" wheels. For the past 2 years, I've been running 37" BFG KM2s on 18x9" Method Double Standards with 1.25" Spidertrax wheel spacers.

Note: This is for my Tundra (supercharged with stock towing 4.30 gears but will be regeared to 4.88 eventually).

 

I believe that Falken makes a 40" A/T or at least they used to. But those may have just been for 17's only.

Looks like BFG makes a 40/12.50/20