So I’m trying to buy a few inches of height to squeeze a boat into a garage for winter storage, has anybody come across a tire that has a small diameter? Maybe something solid rubber? Not looking to transport it just back it into a garage...

How much room do you actually need? if couple inches, deflate tires then air up once through the door. Or if multi axle trailer, pull of one set of tires to sag the springs on remaining axles more.

I seen a cottager literally swap out trailer tires for a set of steel rims right in front of the garage door in order to back it into the garage on 2 strips of Conveyor belting (then reinstall the tires) for the winter.

Not pretty but I assume it works for them

6-8"

Oof. That's not a small amount. That's basically take all tires off and slide in on floor jacks or dollys territory.....Hopefully the concrete floor is very smooth.

..... And you still have to consider cross members that are below the main trailer frames that hang down to catch.... Good Luck!

So many options...

I have squeezed a big Pontoon boat under a 10' tall door by taking the tires off of one of two axles. All the weight settles on the one axle, to slide under the door; then put the other two tires on.

You can lower the tongue of the trailer to the ground, with a cheap adjustable drop hitch, or buy a drop hitch for a lifted truck. That could lower your windscreen (highest point) by 6" or more.

You can let air out of the tires to the point that they barely roll.

You could back the boat onto the garage floor, then take the wheels/tires off, and set the trailer frame on machinery movers. Or you could set the axles down on tire dollies.

If you have a gravel driveway, you can dig out at the right distance where the REAR axle of the truck dips down enough that the windscreen clears the garage door.

You could do a combination of the above.

what about a few of the small doughnut spare tires for cars, if the bolt pattern is right, just for backing up.

ok so measured again, 8'10 door. 9'2 from top of windshield to ground.... little better...

kinda what i was thinking almost like a forklift tire low profile...