With a new tube from Vans, the valve stem on these is too long; this is because the front hub is different to the hubs on the main wheels for which this tube is designed. The main hubs have the hole for the valve stem cut into both halves of the hub so the opening is in the middle. In the front hubs the opening is only cut on one side so the valve stem is not in the midline. I decided it would be worth fitting the tube the other way round, this involved drilling a new hole for the valve in the opposite face of the hub. If you put the assembled hub in a drill press, you can use the original vale hole as a guide. Took five minutes and worked very well. Also all the inner tubes on the plane are the same now so I only need one spare.