I know a few people have modified tires

I've modified 3 tires (Klaw rear, Klaw front, Bonti ACX) using a serrated steak knife. Mounted on the rim, aired up only moderately (20 psi?) to prevent the tire from exploding in my face in case the knife slipped, but still enough for the tire to hold its shape. Took about 45 minutes per tire. In each case, I trimmed off the center and transition knobs almost entirely, leaving the side knobs intact. This was for my intended commuter use of 80-90% pavement at high pressure, and 10-20% offroad in mud and gravel at low pressure.

Of the 3 tires I modified, only 1 survives. The failures are NOT related to my modifications.

• Rear Klaw: sidewall failure. Was nearly worn out when I modified it, which was why I had chosen it for my first experiment in tire customization anyway.
• ACX: sudden, violent death due to bead failure. Known problem with this tire, again unrelated to the modifications I made. Good thing it was on the back though, not in front. I was going 22 mph on pavement when it blew.
• Front Klaw: still rolling. Compared with most semislicks, the massive side knobs I've left on this tire really dig in when it's aired down, yet it still rolls like a slick on pavement. I'm a little nervous about running it on front though, because I accidentally trimmed 2-3 of the knobs a bit too short, below the casing. Will have to watch very carefully for bulges there.

Ginsu and belt sander here

Did two tires, one with a belt sander 80 grit paper and one with the old trusty Ginsu knife (slices, dices, trims knobbies!)

The belt sander was pretty good, it made the short little "knobby remnants" slightly ramped either way depending on which way you ran it. I backed the bike up to a stair and held it upright with my legs as I managed the sander with both hands. A little hard to get the side knobs-I wanted the center and transition knobs short and the edge knobs tall-but it was pretty good.

Then used the Ginsu the second time, not a smooth cut and not uniform but could trim each knob pretty well (center and tranny knobs) w/o shortening the edges. Still, it took longer, wasn't as even, and didn't ramp the knobs like the belt sander so I'd prolly just use the sander again

Or just get Stans new tire, it has really small knobs stock and is light.

Do It!

Belt sander:
I took a belt sander to my Jones ACX, grinding them down to the cheverons. I put the wheel in a truing stand and held the belt sander at 10-20° from parallel to the hub's axis. This allows the wheel to spin slowly. If you push to hard the wheel will shimmy/ shake violently out, if you don't push hard enough you will be there for an entire 6 pack. The shop vac will be needed after this project is done. Also use a mask and cover your beer when using belt sander, the rubber dust is very fine.

X-acto awl:
I used this to cut more edges on the shaved down blocks, straight forward on the front and at 45° on the rear. This provides a little more traction and made little "rat turd" rubber pieces that I'm still finding in my garage This tool is easy to control the depth of cut.

Would say that these modified ACX tires roll as fast as the Nano, but lose little of their original cornering characteristics. They SUCK in mud, but can't be beat in the dry.