The main difference between the DT Swiss GR1600 and 1800 wheels lies in the construction and the materials used. The GR1600 are designed for gravel riding, while the 1800 series is often optimised for other applications such as road or mountain biking. Here are some of the main differences: - Rim height and width: The GR1600s have a rim height of 25mm and an outside width of 28mm, making them suitable for wider tyres and gravel riding. The 1800 series may have different dimensions depending on the specific model. - Weight and material: The GR1600 are often heavier and more robust than the 1800 series, which may use lighter materials to reduce weight. - Application: The GR1600 are specifically designed for gravel riding, while the 1800 series may be designed for other applications such as road riding or mountain biking. - Price: Prices can vary depending on model and application, with the GR1600 often being cheaper than the 1800 series. As I don't have specific information on the 1800 series, I recommend consulting the official DT Swiss website to see detailed comparisons.