I learned some stuff over the last week or so an thought I'd share. If you have conflicting information, please feel free to debate. For anyone who dabbles between trials, big bikes, and sometimes switches tires between bikes, here are my observations: If you put a tubless michilen x11 on an 18" tube type rear excel rim, it stretches the diameter of the tire, making it impossible to fill with air when mounted back on the tubless trials bike. If someone has had success wth this let me know but it seemed like there was 5mm of clearance all around the rim so there was now way to get an air seal on either side. Possibly a cherry bomb would work but I didn't want to try it in my garage. If you run a "Tubliss" TM system on your big bike you cannot get a tubless michilen x11 to seal well. It burps air at about 30psi when you're trying to seat the bead, then never really holds air, even at low pressure. It's probably ridable but you lose about 1 psi every 10 minutes. If you've tried either of the above and need a plan B, the Bridgestone heavy duty tubes are damn near impossible to flatten. I unknowingly pinched the tube between the rim lock and an x11 tubless tire and rode two hard rides. When removing the tire to switch it out, I noticed that the tube was pinched. It had a mark in the shape of the rimlock but was completely fine. I'll try and come back to attach a picture of it. wow.