The urethane tires trim no different than sponge. One thing that's keeping me from giving it a big thumbs up is that it seems that on my unit at least the stub axles seem a little larger than 3/32 in making it vary hard to take the wheels on and off. In fact I thought my Pro Track tires were stuck for good
When I calibrated your unit, I used JK tires and they went on and off easily.
The problem is 3/32" wheels vary quite a bit.
If Geary's axle guy makes them to fit the smallest / tightest ones, guys who use primarily ones with a bit looser bore,
will complain that they are getting wobble.
I just tried a 1/32 Slot-it wheel on all the units I haven't shipped, and they go on easily, and are on the verge of being loose.
You just have to dress it down to fit the tightest tires you are going to use.
Especially if use forced on some rims, you probably galled the axle a bit and need to clean the aluminum off.
Turn the unit on and wrap something close to 240 sandpaper on the stubs and dress them down a little at a time, until the tightest
of the wheels you use, will slip on.