I dont run them because I think it gives my rigs a "24 hour Le Mans" look, you know how those cars look about 17 hours in to that race when the sun is beginning to come back up! They look dirty and hardened! Brake dust, exhaust deposits, paint scratches etc. it gives it that look of character! I almost never wash my car bodies just because it looks so good! But if you absolutely have to run one, you can go down to a hardware store and but some clear flexible tubing that should fit tightly over the tip so it won't come off, or car fuel tubing works.