Internal Sliding gate wheels offer to hide over half of the wheel inside the RHS Tube and the bottom rail of the sliding gate, it also protects the wheel and bearings from dust and water. The question I always seem to be asked is whether the 60mm wheel is better than the 100mm, My reply is based on fact.
The smaller wheel has to turn more times them the larger over a 3 Meter distance and there is a number of bearings in the bearing housing in a 100mm sliding gate wheel than in a 60mm wheel. And try if you can always buy double-bearing wheels, not single-bearing wheels.
External Wheels for Sliding Gates
For both Steel and Timber Sliding gates
Nylon Sliding gate wheel
U Groove wheel with no holding bracket
These wheels require a type of housing to hold the wheel. They are sold as-is.
Price includes the bolt and nut
Measurements shown here are the diameter of the wheel
Double bearing wheels have 2 bearings each side of the wheel able to carry twice the weight of a single bearing wheel.
In Most cases 2 wheels are enough for Sliding gates up to 5M, if you want to add any extra wheels 2 at each end 200-300mm apart would be better then adding a third wheel in the middle. A middle wheel would take all the weight if there is any rises in the floor track and would shorten the life of that wheel. 2 wheels or 4 wheels is the right way to do this.