Can you run rim screws when there is a slight clearance between the screw and the hole?

I have a few that aren't bottomed out. Been like that for years. Haven't had any problem's.

Ideally you want them secured in the rim, purpose is to "pin" the tire to the rim, not so much as to bolt the tire to the rim, thats generally when you have problems.

I screw to the rim.. the screw screws/pokes
into the tire

I can relate to your question, my old rims had a small lip at the edge that the head of the screw hit first. It never cause a problem just looked like the screws were loose. 40 years ago I had a set of mag wheels that used large pop rivets instead of screws, they stuck through the rim about a 1/4" . When the slick was removed the rivets had imbedded into the bead and held just like a screw . No broken screws, no screws unscrewing and no fighting trying to screw the screws into the tire bead. Just a thought of something different.

The rims my friend has have been drilled so the Moroso screws slide in, rather than being around 0.040" smaller than the screw itself. I'm wondering if I should try and find some slightly larger OD screws

Yes, that is what you should do. Screws should "bit" in to the wheels and just protrude in to the rubber bead area.

when i was screwing my rims i used Tek screws & put them in using the cordless drill. easy to install, easy to remove. I gave up screwing my rims a few years back. i just watch a mark i put on the rubber move on the first meeting, swap sides so the mark moves back, but it never gets right back before those slicks are toast. thats doing 1.29 60's.

hello,
my screw holes were worn out from changing slicks several times, I hit the hole with a blunt end punch and it made the hole smaller/tighter. this was with aluminum wheels
gary

I've been told by the old Firstone race tire rep to not bottom the rim screws down flush and leave them that way, he said to bottom them and then back them out 1/32 to 1/16 turn or so. When I switch to M/T tires they verify to do that also That was over twenty years ago so things may be different now. Contact the tire company your using and let us know what they say to do now

I ran Firestone slicks for a couple of decades, then Phoenix. The bead was/is so laden with steel, the moroso screws thread into the tire. The original sheet thread in the rims, formed by the screws, went away 20 pairs of tires ago. I've not had any problems.