I use that silicone rubber tubing Cut to your need diameter, make a small connector, and presto. Won't react with the tire over time either. I get mine from work, but you can pick this stuff up pretty cheap at any craft store.
I had a buddy stationed on a sub tender at Holly Loch, Scotland. He used to watch them get under way and count the seconds between the sail going by, till he saw the tail plane pass. He was Thunderstruck at just how BIG that sub was. I think all he had seen up to that point was fast attacks, no boomers.
I wish i could post photo's, but i'm not that smart.can't seem to figure it out. i usually make a mess of it. Yep. its the Mk iv. Its a really cool kit. Being motorized, it doesn't take away trom the kit at all like the older Tamiya tanks. The price was abit steep, but i had to have it.