Help me diagnose this problem

I’m having a problem with my 24 inch Torker highlighter. Recently, the tire started feeling really squishy, no matter how high I put the pressure and I was having to fight twice as hard to keep the uni from getting out from under me. Since the tube had a slow leak anyway and the tire was bald, I just went and got a new tube and tire, thinking that whatever was wrong would be corrected, but it wasn’t. Same problem. Any suggestions?

first thing that comes to me is check your bearings and make sure they are not giving out when your riding

How do I do that?

THe wheel isn’t wobbly at all by the way.

Check your uni for any loose parts.
Cranks, bearings, seat, spokes, seat post, etc…

I’ll bet on one of the first two.

You do know that higher pressure results in a twitchier/more sensitive ride right?
New slicker tire + higher pressure (maybe + a lack of current riding?) = squirrelly unicycle.

R = Right. And when R is no right it’s wrong.

My bet would be on your spokes needing tightening.

My general “my unicycle feels weird”-procedure.

Check if seat is straight, and tight.
Adjust and tighten if necessary.

-Check if cranks and pedals are tight.
Tighten if necessary.

-Check if frame is loose. (wiggle the bearing holder with your hand to find out which one is loose, if the frame is loose)
Tighten if necessary.

-Check if wheel spins freely. (In an ideal case, it will spin multiple revolutions with just a light push. If not, either your bearing holders are too tight, or bearings are broken).
Loosen bearing holders if necessary, but check if frame is still tight enough.

Check tire pressure. I’d just sit on it and see how much the tire compresses
Adjust if necessary. Both adding or letting out some air if you are convinced it’s the tire, since both can really change the feel.

Check spoke tension, and wheel for being true
Tighten/true if necessary.

Doing things in this order is a mixture of starting with the (in my experience) most common, and a sensible order (first tighten bearing caps if necessary, then check if wheel is still moving freely).

If the unicycle still feels weird afterwards, it’s either the tire pressure being different then they are used too, the ground/other sorroundings being new, or something weird. (Usually a bend crank/pedal, but for example I had a tire with a broken bead recently, it felt weird and I adjusted my tire pressure up and down multiple times until the wire poked through the inner tube, and I finally saw the issue while patching the tube.)

Where is the bearing holder and how do I get to it to wiggle it?

the bearing holder is the halfround looking clamp at the bottom of the fork that holds the wheel on. the bearings sit inside, half inside the fork and the other half held on by a clamp on each side

It’s probably your spoke

If it’s your bearing at most the “movement” might be like .030" or .060". Can you even feel that? Seriously, with pneumatic tires? Not likely.

I’m 90% sure it’s your spokes. I think someone else brought that up. Go to a bicycle shop and let them “check” on their spinning balance fixture.

You will know immediately. Keep on.

Spokes can be checked quickly without the effort or cost of visiting a bike shop. Spin the wheel to see if is runs relativity true and straight. If it is running true, pluck each spoke and note the tone or pitch of each. All the spokes should be about the same musical note or tone. If any are loose it will be very oblivious. If the wheel is not true or if the spokes are not tensioned correctly, then a trip to the bike shop may be in order if not comfortable correcting the problem.

Here is a link with some more details on checking the spoke tension by ear:
If you are tone deaf like me you can use a smartphone app to read the pitch directly or other frequency/pitch measuring devices are available.