Yimatzu Tracker 18x2.50 / 64-355 tire (sometimes colloquially referred to as 2.50x18 but not to be mistaken with a tire that fits on an 18 inch rim). Most commonly used for (but not limited to) electric and gas powered scooters, ebikes and mobility scooters. Inner diameter 35.5cm (13.9 inch), outer diameter 48.5cm (19 inch)