Most Garden Tractors or Riding Lawn Mowers are pretty slow moving even though it seems faster when on the grass but when you get the riding lawn mower or garden tractor out on the road it seems to go slower even at the same speed.
The average garden tractor or riding lawn mower travels at an average speed of 1 to 4 miles per hour.
Some people have been able to get their riding lawn mowers up to a speed of 8 to 10 mph by modifying the engine and trans axle of the lawn mower.
If you modify the lawn mower even more you can get it to go around 35 to 45 mph but you need some good modification to the lawn mower and the engine which can lead to damage to it.