Very strange indeed. Only smaller tyre valves than the standard car/bike Schrader's I've seen are on pushbikes, the Presta type.
There are two main types of bike tyre valves: Schrader and Presta. Schrader valves are similar to those found on car tyres, while Presta valves are thinner and have a threaded top that must be unscrewed before inflating. The valve type can typically be determined by looking at the valve stem, but it is always a good idea to double-check before inflating.