Leak stop tube 8a nose wheel

Vans uses a weird tire tube size for the 8a nose wheel ( lamb tube) 11x4.005.

I want to replace this with a Goodyear or other brand of leak stop type tube.
Any suggestions?

Couldn't find this size under desser, Michelin or Goodyear.

Thanks,
Tom H

Tom,
It's not really a weird tube size, it is just not a standard tire/tube size to aviation (other than the home built side).
It first became popular as the main wheel tires/tubes on the long-eze.
It has been used on many other aircraft since then, and is the nose wheel tire/tube for all the two seat tri gear RV's except for the RV-12 (and now RV-14A)
Because it is not commonly available, new finish kits are delivered with two nose wheel tubes so that one can be carried as a spare.

As far as I am aware, no one makes a leak stop tube in the proper size.