Michelin Ultra Heavy Duty Tubes These heavy duty reinforced tubes are for off-road applications and provide enhanced protection against punctures and pinch flats. Features: Reinforced tubes for off-road applications Features 4mm wall thickness Provides enhanced protection against punctures and pinch flats Tr-4 Straight metal stem with 8mm diameter Note: Not highway safe, for offroad use only. Tr-4 and Tr-6 valve stem styles can be used interchangeably.