I'll admit I run at least half of my engines without the traction tires. Especially the heavy ones. They don't seem to need them! Now if you were running uphill a lot I could see the need for them possibly. I myself have a pretty level layout with no inclines, though even a slight incline shouldn't matter. So far each time one comes off I just take it on off and run the engine without. I haven't had any slippage so far. I would leave them off next time they come off and watch to see if you have any slipping of the wheels, and if not you're good to run without I'd say!
I am/was in the same boat as you and as they fell off just left them off! All of the ones who lost them are doing fantastic if not better so far because there isn't anything to hang up in the running gear of the steamers!
