Several big vehicle tyres, such as those used on buses, heavy lorries, and tractors, are intended to be used with inner tubes. To avoid air leakage, inner tubes are torus-shaped balloons constructed of an impermeable material, such as soft, elastic synthetic rubber. To maintain air pressure, the inner tubes are placed into the tyre and inflated. For the last 50 years, our inner tubes have been sold to over 140 countries worldwide as our hallmark product.